2026-09-28T08:09:58Z http://oai-pmh.copernicus.org/oai.php

oai:publications.copernicus.org:tc139769 2026-09-25 tc

Paul, Daria Caus, Danu Keil, Paul Kadow, Christopher Arndt, Stefanie Snow on Antarctic sea ice strongly affects thermodynamic processes, sea ice mass balance, and microwave remote sensing, yet its spatial variability and characteristic length scales remain poorly quantified. The aim of this study is to provide a spatially extensive, layer-resolved characterization of Antarctic late-summer snow on sea ice and, for the first time, to quantify the variability of snow properties and their horizontal correlation length scales on first-year (FYI) and multi-year ice (MYI). We use a unique combination of manual snow pit observations and more than 900 SnowMicroPen (SMP) profiles collected along meter-scale transects during three expeditions in the Weddell Sea between 2018 and 2021. Snow stratigraphy and microstructural classes were derived from SMP force data using a supervised one-dimensional convolutional neural network trained on manually classified SMP profiles. Across both sea-ice regimes, intrinsic properties of individual snow types, including density and specific surface area, were broadly similar. Differences between FYI and MYI instead arise from contrasting snowpack structure, snow type fractions, and spatial coherence, with MYI characterized by a higher prevalence of dense melt-freeze layers and enhanced vertical heterogeneity. Spatial autocorrelation analyses reveal pronounced scale-dependent variability, with snow properties on FYI decorrelating over short distances, while MYI exhibits substantially higher spatial coherence. Individual ice floes capture only about 50 % of the snow density variability characteristic of their respective ice regime, underscoring fundamental limits to the representativeness of point measurements. A hierarchy of variability emerges, in which snow type fractions and layer thickness dominate snowpack heterogeneity, while bulk snow density is comparatively homogeneous across spatial scales. These results demonstrate that Antarctic summer snow variability is governed primarily by stratigraphic composition and ice-regime-dependent snowpack evolution rather than bulk-integrated properties. These findings emphasize the need for spatially distributed observations and stratigraphy-aware parameterizations to improve the representation of snow on Antarctic sea ice in remote-sensing applications and sea ice and climate models. In particular, the relative consistency of specific surface area within snow types across ice regimes provides observational constraints that can be evaluated for future microwave-emission and radiative-transfer modeling studies.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/tc-20-5491-2026 eISSN: 1994-0424 eng

oai:publications.copernicus.org:os140699 2026-09-25 os

Ohishi, Shun Miyoshi, Takemasa Kachi, Misako We previously produced the local ensemble transform Kalman filter (LETKF)-based Ocean Research Analysis (LORA) version 1.0 datasets for the western North Pacific and Maritime Continent regions (LORA-WNP and LORA-MC, respectively) during the period from August 2015 to January 2024. However, these limited domains and periods constrain their applicability. Therefore, we developed a new eddy-permitting LETKF-based ocean data assimilation system and produced LORA version 2.0 for a quasi-global domain (LORA-QG) from June 2002, when the Advanced Microwave Scanning Radiometer (AMSR) series, a series of space-borne microwave imagers, began providing sea surface temperature observations and the Argo program substantially expanded in situ temperature and salinity measurements. We validated LORA-QG using observations from surface drifter buoys, tide gauges, and ocean climate stations, and compared the results with those of three eddy-permitting global ocean reanalysis datasets (GLORYS2V4, ORAS5, and C-GLORSv7). Although these observations are independent of LORA-QG, ORAS5, and C-GLORSv7, they are not entirely independent of GLORYS2V4. The validation results show that LORA-QG agrees well with the observations and has the second-highest accuracy among the four datasets in terms of overall root-mean-square deviations relative to the observations, thus achieving sufficient accuracy for geoscientific research and practical applications. LORA-QG provides features unavailable in conventional global reanalysis products, including ensemble-based uncertainty estimates and individual terms of the heat and salinity budget equations. These features make LORA-QG a valuable dataset for ensemble-based ocean forecasting and process-based studies. However, room for improvement remains, as LORA-QG exhibits significant warm biases in the tropics, particularly in the western tropical Pacific, and its sea surface salinity representation is likely limited due to relatively strong salinity nudging toward a climatological dataset in the mixed layer.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/os-22-2915-2026 eISSN: 1812-0792 eng

oai:publications.copernicus.org:os138560 2026-09-25 os

Song, Zhe Cazenave, Anny Llovel, William Storto, Andrea Bouih, Marie Based on satellite altimetry, GRACE space gravimetry and Argo-based steric data down to 2000 m, recent studies have shown that the North Atlantic sea level budget (i.e., altimetry-based sea level minus sum of components) of the past two decades is not closed, with strong regional residuals in the North Atlantic. In this study, we revisit the North Atlantic sea level budget, using satellite altimetry, GRACE and GRACE-FO data, different Argo products and an ocean reanalysis (CIGAR) over the 2004–2022 time span. The ocean reanalysis is used to estimate the manometric contribution, an alternative to using GRACE data, as well as the deep ocean contribution to the sea level budget, not yet fully sampled by Argo. Analyzing different data sets allows us to assess their impact on the previously reported non-closure of the North Atlantic sea level budget. We first find that using the CIGAR ocean reanalysis-based manometric component significantly reduces the residuals of the North Atlantic sea level budget compared to GRACE. We also find that accounting for the deep ocean (below 2000 m) thermal expansion (using the CIGAR reanalysis) allows for reducing 90 % the North Atlantic budget residuals when using CIGAR for the manometric component. The budget can be closed within the data uncertainties when CIGAR manometric and full depth steric sea level are included.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/os-22-2903-2026 eISSN: 1812-0792 eng

oai:publications.copernicus.org:hess142110 2026-09-25 hess

Zhang, Wenhao Li, Xiaoyan Deng, Yuanhong Hu, Guangrong Shi, Fangzhong Groundwater plays a crucial role in maintaining baseflow in rivers and ensuring water supply, particularly in alpine regions where the freeze–thaw (FT) cycle exerts a strong influence on hydrological processes. However, a systematic understanding is still lacking regarding how FT processes affect the composition of groundwater recharge sources and the transitions among recharge pathways. This study takes the Qinghai Lake basin (QLB) as a case study and combines water isotope and hydrometeorological data to quantify the dynamic characteristics of groundwater recharge sources and pathways during the FT periods. The study found that soil water (57.0 %–76.3 %) was the dominant source of groundwater recharge during the FT periods, followed by rainfall (13.8 %–26.1 %) and snowmelt (7.9 %–22.0 %). The thawing process enhances the vertical connectivity of the soil profile, facilitating the recharge of groundwater from snowmelt and the 60–90 cm soil layer. Furthermore, the lc-excess value of groundwater gradually shifts from values closer to soil water to those closer to precipitation, indicating that piston flow gradually weakens during the process of groundwater recharge by soil water, while preferential flow intensifies, resulting in a pattern where piston flow and preferential flow coexist. Spatially, in the middle and upper regions dominated by permafrost, groundwater is primarily recharged by water from the 0–60 cm soil layer traveling along longer hydrological pathways, whereas in the downstream regions of the basin dominated by seasonal frozen ground, groundwater is primarily recharged by rapid infiltration from the 30–90 cm soil layer. Our research demonstrates that in alpine permafrost regions, freeze–thaw processes regulate water storage and transport, thereby further influencing the recharge sources and pathways of shallow groundwater.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/hess-30-6039-2026 eISSN: 1607-7938 eng

oai:publications.copernicus.org:hess136344 2026-09-25 hess

Mahmoodi, Nariman Merz, Christoph Pickert, Jürgen Dietrich, Ottfried Peatlands play a crucial role in regional water balance and carbon dynamics but are often degraded due to drainage and agricultural use. In Germany, many drained peatlands have shifted from carbon sinks to CO₂ sources. Rewetting these ecosystems is therefore essential to restore their ecological functions and mitigate greenhouse gas emissions. However, effective rewetting requires a detailed understanding of peatland hydrology and its response to climatic and management conditions. To address this need, this study employs a fully coupled surface–subsurface hydrological model (HydroGeoSphere) to analyze the complex hydrological functioning of a typical degraded fen peatland site (11.6 ha) in Brandenburg, Germany. The model-based quantification of hydrological fluxes is basis for assessing peatland vulnerability to climate variability and land use while providing a hydrological baseline for future evaluation of rewetting strategies. The studied peatland is connected to a regional aquifer and intensively drained by a system of ditches. Simulations used daily meteorological inputs and detailed field measurements from 2015 to 2023. Evapotranspiration (ET) was parameterized using field-measured vegetation dynamics (seasonal leaf area index and management schedules), while measured ditch water levels served as hydraulic boundary conditions. The site was spatially divided into different management units with distinct vegetation parameters. The peat profile was represented by two layers (a 0.3 m highly degraded surface peat overlying a 0.7 m less degraded layer) overlying sand (aquifer) and till (aquifer base). The model was evaluated from different angles against eddy covariance ET and groundwater table dynamics during a calibration period (2016–2020) and a validation period (2021–2023) using a multi-metric approach. The model successfully reproduced seasonal water-table fluctuations and ditch–peatland interactions, including ET-driven hydraulic gradient dynamics between summer and winter. Simulated ET closely matched eddy covariance measurements, with RMSE values of 64 mm yr⁻¹, 10.2 mm month⁻¹, and 1.01 mm d⁻¹, and showed only minor biases during dry conditions, while over the year seasonal dynamics of ET were also well captured by the model. The model reproduced groundwater variations with sufficient accuracy, achieving KGE values of 0.80–0.85, NSE of 0.83–0.86, and RMSE of 0.15 m during calibration and validation. The analysis of seasonal and interannual water-storage changes showed pronounced shifts between hydrological surplus and deficit, demonstrating that drained fens are highly sensitive to evapotranspiration demand and prolonged drought. The modeling approach captured key hydrological processes with high robustness. The modelling framework provides a hydrological baseline and a basis for future assessment of peatland rewetting measures. These findings support ongoing restoration initiatives on drained peatlands in Europe.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/hess-30-6019-2026 eISSN: 1607-7938 eng

oai:publications.copernicus.org:esd138613 2026-09-25 esd

Schwinger, Jörg Merfort, Leon Bauer, Nico Bernardello, Raffaele Butenschön, Momme Bourgeois, Timothée Gidden, Matthew J. Gupta, Shraddha Lee, Hanna Mengis, Nadine Moustakis, Yiannis Muri, Helene Nieradzik, Lars Peano, Daniele Pongratz, Julia Sauer, Pascal Tourigny, Etienne Wårlind, David Assessing Earth system responses arising from carbon dioxide removal (CDR) requires developing and simulating pairs of scenarios – a mitigation scenario with deployment of CDR and a corresponding no-CDR baseline. The latter describes a world where no CDR is deployed, such that net carbon emissions are higher and a given temperature target may be missed. While over the past years a rich literature on mitigation scenarios with CDR has been emerging, no-CDR baselines have mostly been explored in stylized Earth system model (ESM) experiments. In such simulations, a no-CDR baseline simply assumes that CDR is “switched off”, while socio-economic constraints are not considered. However, the deployment of CDR in mitigation scenarios, created by integrated assessment models (IAMs), is embedded in a consistent socio-economic description of plausible futures, and disallowing CDR may affect climate drivers due to changes in the energy system and in land-use dynamics. Particularly, when moving towards an activity-driven representation of CDR in emission-driven ESMs, where the activity that draws down CO₂ from the atmosphere is explicitly modelled, the creation of no-CDR baselines comes with challenges and trade-offs. Here, we conceptualize a framework for emission-driven ESM simulations of IAM scenarios that allows us to determine carbon-cycle feedbacks and biogeophysical effects of CDR deployment using no-CDR baselines. We show that different options exist for the creation of no-CDR baselines, which offer different insights and have their specific advantages and limitations. We also demonstrate that internal variability of the climate system inherently limits our ability to detect the small signals related to CDR deployment and its feedbacks. Hence, unless a sufficiently large initial conditions ensemble is employed, stylized modelling approaches may remain preferable for some applications, e.g., the quantification of regional biogeophysical effects of CDR deployment. Both, the efficiency of CDR (defined as CO₂ removed per unit of resources employed) as well as related carbon-cycle feedbacks and biogeophysical effects are expected to be scenario- and model-dependent. Our simulation design of concentration- and emission-driven no-CDR baselines, together with an improved representation of CDR in the IAM – ESM modelling chain, opens an avenue towards estimating CDR efficiencies and their uncertainties under various future scenarios in upcoming model intercomparison activities.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/esd-17-1341-2026 eISSN: 2190-4987 eng

oai:publications.copernicus.org:esd141092 2026-09-25 esd

Thomas, Rhidian Compo, Gilbert P. George, Steve Hegerl, Gabriele C. Schurer, Andrew Shepherd, Theodore G. Slivinski, Laura C. Thompson, Vikki Hawkins, Ed How would the weather of a year from history be experienced in a warmer world? We reconstruct the weather of 1903 using a reanalysis system that assimilates only surface pressure observations (20CRv3) with observed SSTs, and then reconstruct it again with increased SSTs and atmospheric CO₂ levels. By assimilating the same pressure observations, the reanalysis experiments produce the same weather patterns, and so we translate the weather of 1903 into a warmer context. We focus on changes in the everyday weather of four regions with a high density of historical pressure observations, where the circulation is constrained and differences between the experiments are due to the thermodynamic component of climate change. In these regions, nearly all days are warmer in the warmer world experiments, but the largest increases occur on cold days (below freezing) and hot days (above 20 °C). Daily rainfall becomes more variable, even in regions where total rainfall is reduced. Fewer days experience light rain while more days experience heavy rain, and rainfall only increases on less than 1 d in 10. This single year pair of reanalysis experiments also recovers common patterns of observed and projected long-term changes. For example, Western Mediterranean precipitation declines outside winter, but shows a small increase in winter in the absence of storm track shifts. By anchoring our analysis in weather patterns that have actually occurred, the reanalysis experiments point to how our day-to-day experience of the same weather patterns may change in a warmer world, even if the weather patterns themselves do not.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/esd-17-1365-2026 eISSN: 2190-4987 eng

oai:publications.copernicus.org:eo140575 2026-09-25 eo

Bredal, Marie Rouyet, Line Wendt, Lotte Hindberg, Heidi Stødle, Daniel Lauknes, Tom Rune Oostveen, Jelte Larsen, Yngvar Aslan, Gökhan Hauglin, Emma Dehls, John Sundal, Anja Odh, Anna Moldestad, Dag Anders The InSAR Svalbard Ground Motion Service (GMS) provides open-access surface displacement maps and time series in the Svalbard archipelago, derived from Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR). The service provides seasonal products capturing short-term 2016–2024 displacements and interannual products documenting long-term 2018–2024 velocity trends. InSAR Svalbard covers five areas on Spitsbergen Island (Longyearbyen, Ny-Ålesund, Svea, Hornsund and Kapp Linné). The service consists in a web-based visualisation tool at https://svalbard.insar.no/ (release date: 2 February 2026, last access: 22 September 2026). The products are also distributed at https://doi.org/10.5281/zenodo.18442696 (Bredal et al., 2026a). InSAR Svalbard establishes a foundation for geohazard assessment in Arctic regions and interdisciplinary research on permafrost dynamics, ground stability, and environmental changes.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/eo-1-121-2026 eISSN: 3054-1786 eng

oai:publications.copernicus.org:gmd135993 2026-09-25 gmd

Picard, Ghislain Murfitt, Justin Zakharova, Elena Zeiger, Pierre Arnaud, Laurent Aublanc, Jeremie Landy, Jack C. Scagliola, Michele Duguay, Claude Radar altimeters are essential tools for observing the cryosphere, especially for estimating ice-sheet elevation change and sea-ice thickness. However, retrieving these quantities remains challenging, and progress depends on physically based numerical simulations of the recorded waveforms to understand their sensitivity to the geophysical parameters of the medium. Such models can also guide the design of future satellite missions. Accurate simulations require a balanced combination of a realistic description of the medium, precise calculation of wave–medium interactions, and an accurate representation of the altimeter measurement process, including downstream processing. The Snow Microwave Radiative Transfer (SMRT) model has addressed the first two aspects for a decade and includes an altimetric Low Resolution Mode (LRM) module, but has, until now, lacked a delay-Doppler (SAR) altimetric capability used by most modern sensors. This study introduces the new SMRT SAR altimetry module, which operates in three steps. First, it calculates the backscatter of all layers and interfaces using existing SMRT modules. Next, it models the waveforms of each layer and interface using a delay-Doppler approach. Finally, these components are combined to produce the final waveform. The user selects the delay-Doppler model from one of eight formulations reviewed, implemented, and compared in the literature. The validation first assesses these models under simple conditions, confirming they produce consistent results but differ in computational efficiency and flexibility. Subsequently, the new module is compared with external models to confirm its accuracy. Finally, it is applied to Antarctic conditions, where the simulations reproduce observed Sentinel-3 waveform variability linked to surface roughness. The open-source module, equipped with the eight options, now enables a wide range of numerical experiments, from studying penetration bias to exploring the potential for snow retrieval on sea ice and lake ice thickness.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/gmd-19-9103-2026 eISSN: 1991-9603 eng

oai:publications.copernicus.org:essdd145385 2026-09-25 essdd

Domergue, Salomé Rodier, Martine Dupouy, Cécile Duphil, Maxime Varillon, David Delepierre, Amandine Desnues, Anne Fiat, Sylvie Menkes, Christophe https://www.mio.osupytheas.fr/fr/moise-mouillage-lagonaire-instrumente-suivi-biogeochimique/, last access 26/08/2025) was surveyed with moored instruments and monthly visits providing unique long time series of hydrological and biogeochemical measurements in approximately 10m depth. The MOISE program objective was to characterize lagoon environmental variability across monthly, seasonal, and interannual timescales at a site potentially impacted by river outputs. Here we provided a 13-year quality-controlled dataset with vertical profiles of temperature, salinity, and chlorophyll-adjusted fluorescence from CTDs and continuous currents from a moored 600 kHz Acoustic Doppler Current Profile (ADCP).
This site represents the unique location in New Caledonia lagoon to deliver an extended multi-parameter time series of long-term monitoring of the lagoon’s environmental state and circulation dynamics. The length of the time series allowed the depiction of the ENSO impact (El Niño-Southern Oscillation) on the interannual variability. A clear seasonal cycle was also observed, with higher chlorophyll during austral summer when temperatures are highest, salinity lowest and wind-driven currents strongest and predominantly directed toward the west-northwest. MOISE data further highlight the strong influence of extreme events such as tropical cyclones, tropical depressions and heavy rainfall, on the lagoon, which can induce temporary stratification of the water column that is otherwise generally homogeneous.
The dataset was post processed, quality controlled and is available in netcdf on SEANOE in open access (SEA ScieNtific Open data Edition) at the following DOI : https://doi.org/10.17882/98821. ]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/essd-2026-653 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essd138431 2026-09-25 essd

Gamot, Juliette Delepoulle, Antoine Nencioli, Francesco Pujol, Marie-Isabelle Dibarboure, Gerald This study introduces the new global Mesoscale Eddy Trajectory Atlases, META4.0 available in an AVISO repository at https://doi.org/10.24400/527896/a01-2026.001 (CLS and CNES, 2026). META4.0 provides eddy detections, trajectories, and interaction networks derived from satellite altimetry. Eddy detection relies on the pyeddytracker (PET) algorithm (Mason et al., 2014), further optimized by Pegliasco et al. (2022), and represents a substantial improvement over the previous META3.2 product (SSALTO/DUACS, distributed by AVISO+ with CNES support).

The main advance of META4.0 is the explicit identification of eddy merging and splitting events. By combining grouping, which links detections across consecutive days, and segmentation, which tracks continuity through interaction events, trajectories are organized into networks of interconnected eddies. This network-based representation complements the single-trajectory view of eddy life cycles by explicitly accounting for eddy interactions.

The paper presents both diagnostic tools designed to explore individual eddy networks (e.g., timelines, spatial trajectories, and eddy properties such as effective radius or shape error) and the results of a global statistical analysis over more than three decades. These tools and analyses offer new diagnostics for investigating network properties, eddy lifetimes, and the spatial and temporal distribution of merging and splitting events of the META4.0 atlas. Clustering analyses reveal recurrent interaction patterns and identify regions where eddy networks are particularly active. An independent dataset of surface chlorophyll concentration is used for qualitative validation of selected events. Finally, Lagrangian advection of synthetic particles highlights coherent forward and backward transport signatures associated with interaction events, providing a physical validation of the reconstructed networks.

Overall, META4.0 offers a novel and physically consistent framework to characterize mesoscale eddy interactions and to better understand their role in shaping ocean dynamics.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/essd-18-7043-2026 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essd137122 2026-09-25 essd

Liao, Yuanhong Chen, Shuang Bai, Yuqi Wang, Jie Gong, Peng Accurate annual information on cropland extent is essential for monitoring agricultural change, yet existing global products are often limited to snapshots or multiyear epochs and differ in their cropland definitions. Here we present GACED30, which, to our knowledge, is the first dedicated global 30 m annual cropland-extent dataset covering 2000–2024. The mapping framework combines gap-free SDC30 observations, spectral-semantic alignment of expert-annotated and spatially augmented samples, and rule-based spatial and temporal refinement. Independent classifiers were trained for each year using a common observation, feature, sample-construction, and modeling protocol, and the resulting annual record was used to derive pixel-level Cropping Frequency and 1 km Structural Evolution Indicators. Against independent stable-site FAST-Crop samples, GACED30 achieved an overall accuracy of 0.965 and an F₁ score of 0.844. Multitemporal assessments using GLAD Cropland and LUCAS reference samples showed higher recall and F₁ scores than GLC_FCS30D for both crop gain and crop loss, although the absolute transition scores remained modest. In a matched regional assessment in China, GACED30 achieved OA and F1 scores of 0.946 and 0.840, respectively, showing performance comparable with CACD. At the national scale, GACED30 agreed closely with definition-reconciled FAOSTAT statistics (R²: 0.95; area-weighted direction match rate: 83.1 %). The sample-adjusted global cropland area was estimated at 1488.5 Mha in 2024, approximately 30.0 Mha higher than in 2000. Persistent expansion was concentrated in parts of Africa and South America, whereas stability and reduction were more widespread across much of the Global North. GACED30 provides a harmonized baseline for monitoring global cropland-extent dynamics and is publicly available at https://doi.org/10.5281/zenodo.18199675 (Chen et al., 2026).

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/essd-18-7071-2026 eISSN: 1866-3516 eng

oai:publications.copernicus.org:angeo138728 2026-09-25 angeo

Nanjo, Sota Kurita, Satoshi Sergienko, Tima Miyoshi, Yoshizumi Kataoka, Ryuho We report wide-field observations of flickering aurora obtained with a fast sCMOS camera and a diagonal fisheye lens at Poker Flat Research Range, Alaska, on 8 February 2016. The system recorded 512×512 pixel images at 80 Hz, enabling us to investigate the mesoscale organization of flickering along a discrete auroral arc over spatial scales of several hundred kilometers. Flickering occurred intermittently with dominant frequencies between 3 and 20 Hz, most commonly within a narrower band of 4–12 Hz. Spatial maps of the peak frequency reveal that regions with similar periodicities sometimes formed coherent clusters on scales of ∼ 10 km, and that multiple clusters with different frequencies (e.g., ∼8 and ∼13 Hz) could coexist simultaneously along the same arc, separated by ∼150 km. Some of these clusters moved together with the background arc, suggesting that the modulation is closely tied to the local plasma environment and inverted-V potential structures associated with discrete aurora. An automated patch detection analysis showed that, although individual events may locally suggest an inverse relationship between flickering frequency and patch size, this trend does not persist statistically. Instead, flickering at a given dominant frequency occurs over a wide range of patch sizes, with a typical apparent north–south scale of 4.4±2.4 km when projected to an assumed emission altitude of 110 km. These results are consistent with generation scenarios in which electron precipitation is modulated by interference among multiple EMIC waves in the auroral acceleration region, extending previous narrow-field studies to the mesoscale and demonstrating the diagnostic value of wide-field, high-cadence imaging for wave–particle interactions in the auroral ionosphere.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/angeo-44-959-2026 eISSN: 1432-0576 eng

oai:publications.copernicus.org:amt139463 2026-09-25 amt

Schmitt, Tobias D. Sindram, Moritz Löw, Benedikt A. Weis, Lukas Kleinschek, Ralph Bobrowski, Nicole Butz, André Monitoring volcanic emissions is essential for understanding volcanic processes and predicting eruption dynamics. Remote sensing is the only method that allows safe measurements right before, during, and after eruptions. Current monitoring relies on scattered sunlight, whose essentially unconstrained viewing geometry permits continuous and automated observation. It is, however, mostly limited to the ultraviolet and visible (UV-VIS) spectral ranges by the available sky brightness, restricting observations largely to SO₂.

Here, we assess the feasibility of constraining volcanic emissions by passive Fourier transform infrared (FTIR) spectroscopy of sky-scattered sunlight in the near-infrared (NIR), where more gases of interest have absorption features. Combining an instrument model for the spectral signal-to-noise ratio (SNR) with an information-content analysis, and incorporating actual measurements to capture the systematic uncertainties inherent to atmospheric total column retrievals, we estimate detection limits for individual trace gas columns. The instrument model accurately reproduces the results of laboratory validation experiments. We use Mount Etna as a representative high-emission volcano. We find that CO₂ column measurements remain challenging: the plume enhancement is small compared to the high and variable atmospheric background, and little scattered light is available in the NIR. Even under bright skies, reaching a detection limit comparable to the expected column enhancement takes about 5 min, and up to 2.5 h under dark conditions. Plume transects, which require many such measurements at substantially better precision, are therefore out of reach, whereas individual plume-composition measurements remain conceivable. In contrast, the strongly emitted halogen species HCl and HF, whose atmospheric background is low, are detectable within seconds under bright skies and within a few minutes under dark conditions. For these species, a multi-instrument approach makes plume-composition measurements practical: pairing the FTIR with co-aligned UV observations of SO₂ yields gas ratios that, combined with established SO₂ flux networks, give access to the halogen emissions. For CO₂ this route is not excluded, but limited precision and the impact of radiative transfer errors on a background-dominated retrieval make the outcome hard to predict. Finally, this SNR and detection-limit analysis transfers to other instruments, spectral regions, target species, and emission sources.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/amt-19-6145-2026 eISSN: 1867-8548 eng

oai:publications.copernicus.org:amt136997 2026-09-25 amt

Sinyuk, Alexander Eck, Thomas F. Slutsker, Ilya Lewis, Jasper Grigorov, Petar Smirnov, Alexander Schafer, Joel S. Sorokin, Mikhail Lind, Elena Gupta, Pawan Cloud screening algorithms have always been a critical component of Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) Level 1.5 and 2.0 product. The initial cloud screening algorithm in the Version 1 and 2 database was semi-automatic and required involvement of a human analyst to finalize the results. It became fully automatic in Version 3 (V3) due to employing information on the angular shape of sky radiances measured in the aureole (curvature algorithm). Although efficient, the curvature algorithm is threshold based and fails to detect clouds when its parameters are beyond the corresponding pre-determined thresholds. This is especially noticeable at high latitudes where the size of ice crystals in cirrus clouds are sometimes relatively small and therefore comparable in size to aerosols. It is shown that additional information can be extracted from analysis of the smoothness of diurnal variability of sky radiances measured at the 3.3° scattering angle. This measurement is a part of the so-called curvature scan (CCS), which takes measurements from 3 to 7.5° scattering angle with 0.3° steps after each measurement of AOD. The analysis of the diurnal variability of CCS (3.3) for cloud-free conditions shows relatively smooth temporal dependencies, which can be fitted by polynomials with high correlation coefficients while in conditions almost completely dominated by clouds, the temporal variability is completely random. For partially cloudy days, the two main features are observed: relatively smooth aerosol signatures and irregular spikes due to clouds. The new technique is proposed that employs the smoothness of the diurnal variability of the CCS(3.3) scan as a criterion of the cloud free conditions. In the case when both features are present, the idea of the new algorithm is to remove irregular spikes due to clouds while keeping the smooth part due to aerosols intact. The new algorithm detects spikes associated with clouds by comparing magnitudes of CCS(3.3) at neighboring time stamps through calculating their first differences (FD). This algorithm was applied to the CCS(3.3) measurements taken at several AERONET sites. The results were analyzed in terms of net change in Angstrom exponent (AE) as well as number of AOD measurements. The analysis showed the algorithm performs satisfactorily at AERONET sites dominated by fine mode aerosols, however at sites dominated by dust, the algorithm removes a big fraction of cloud-free observations. The issue was corrected by introducing an additional cloud screening parameter. It is based on observation of the different rates in changing of AE with iterations for cloud-free and cloudy conditions with a much higher rate in the former case. The new parameter was selected as a slope of the linear regression between integration number and the value of AE after the corresponding iteration. The algorithm disregards FD algorithm results if the slope is smaller than certain threshold value. Finalizing the FD algorithm threshold setting as well as evaluation of the algorithm performance is done by using independent cloud detection information available from Micro-Pulse Lidar Network (MPLNET) data. The AERONET and MPLNET data were time and space collocated with additional averaging over a one-hour period. The comparison showed that, on average, the FD algorithm outperformed V3 L1.5 by about 0.02 in Matthews Correlation Coefficient (MCC), suggesting consistent improvement in overall cloud detection accuracy. Additional analysis performed in terms of MCC metrics also showed that the FD algorithm achieves a more balanced and accurate classification of clouds vs clear.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/amt-19-6125-2026 eISSN: 1867-8548 eng

oai:publications.copernicus.org:amt135934 2026-09-25 amt

Huang, Ruizhe Wang, Sherrie We present the first global, data-driven analysis of power plant NO₂ plume detectability from space. Using TROPOspheric Monitoring Instrument (TROPOMI) observations (nadir pixel size 3.5–7 km) over 6000 of the world's highest-emitting power plants and hourly Continuous Emissions Monitoring Systems (CEMS) data for 500 US plants, we develop an automated algorithm that labels plumes and attributes them to their sources with 98 % accuracy. For the subsequent detectability analysis, we restrict to plants outside interference zones (at least 20 km from other major power plants and 45–90 km from cities (depending on city size)), which retains 45.0 % of US and 21.1 % of global NO_x emissions in our datasets. We then train a machine learning model to predict plume detectability (the probability of detection given the observation conditions) from meteorological, environmental, sensor, and power-plant variables sampled at the single TROPOMI pixel over each plant (F1 score>0.66, AUC>0.8). Out of 25 variables, we find that NO_x emission rate, surface altitude, surface albedo (NO₂ window), sensor zenith angle, primary fuel type, and wind speed jointly explain much of the variability in detectability. For US power plants, an hourly NO_x emission rate of ≈ 400 kg h⁻¹ corresponds to ∼ 50 % detectability, but detectability varies from < 20 % to > 60 % under different combinations of these conditions. These results provide the first empirical quantification of the physical and environmental factors that govern NO₂ plume visibility in TROPOMI data, establishing a foundation for models to use similar predictors as auxiliary variables when quantifying emission rates from plume appearance.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/amt-19-6099-2026 eISSN: 1867-8548 eng

oai:publications.copernicus.org:acp139798 2026-09-25 acp

Sakata, Kohei Kurisu, Minako Takahashi, Yoshio Atmospheric deposition of aerosol iron (Fe) can stimulate marine primary productivity by supplying dissolved Fe (d-Fe) to the surface ocean, thereby potentially influencing the global climate. Aerosol Fe solubility (Fe_sol%) is closely linked to its bioavailability, and previous studies have shown that Fe_sol% generally increases as aerosol Fe concentration decreases. However, the mechanism underlying this widely observed inverse relationship remains unresolved. In this study, aerosol observations from East Asia, the North and South Pacific, and the Atlantic were compiled, and the enrichment factor of total Fe (EF_T-Fe = (T-Fe

/

T-Al)

_{aerosol} /

(T-Fe

/

T-Al)_crust) and dissolved Fe to dissolved Al ([d-Fe]

/

[d-Al]) were used to estimate the contributions of mineral-derived and anthropogenic Fe to aerosol d-Fe, as well as the Fe_sol% of each source fraction. Aerosol d-Fe was found to be derived predominantly from mineral dust in many oceanic regions. In addition, both mineral-derived Fe and anthropogenic Fe showed inverse relationships between concentration and solubility. If the inverse relationship between Fe concentration and Fe_sol% were controlled mainly by simple two-component mixing between low-solubility mineral particles and highly soluble anthropogenic Fe, the Fe_sol% of each source fraction would not be expected to vary systematically with concentration. Instead, the results suggest that atmospheric chemical processing, together with depositional removal during transport, progressively increases the solubility of Fe remaining in aerosol particles. The ability to estimate the sources and dissolution processes of aerosol Fe from such fundamental concentration data may help improve the parameterization of aerosol Fe dissolution in global climate models.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/acp-26-13505-2026 eISSN: 1680-7324 eng

oai:publications.copernicus.org:acp133449 2026-09-25 acp

Roelofs, Tristan Castellnou, Marc Vilà-Guerau de Arellano, Jordi Janssens, Martin Heerwaarden, Chiel We studied the factors governing the existence of fire-induced circulations ahead of the flaming zone and the impact of these circulations on the thermodynamic structure of the atmospheric boundary layer. To study the circulation, we used MicroHH to create a high-resolution (25 m) turbulence-resolving 3D large-eddy simulations (25.6 km×38.4 km) of a stationary fire under realistic atmospheric conditions. The setup was inspired by field observations of fire characteristics and a radiosonde from the Santa Coloma de Queralt fire (Catalonia, Spain, 24 July 2021). The stationary fire enabled us to isolate the persistent impacts of the fire on the atmosphere.

Our results indicate that the existence of a fire-induced circulation is governed by the wind speed component aligned with the circulation. In our simulations, the circulation consisted of updrafts above the fire, downdrafts 2 km ahead, and reversed surface winds between the updrafts and downdrafts. With higher wind speeds in the direction of the circulation, the reversal of the surface winds decreases. Consequently, the circulation dissipates, since the reversed winds connect the updrafts and downdrafts into a circulation. Hence, explaining why fire-induced circulations are not always present.

The thermodynamic impact of the circulation is driven by the updrafts and downdrafts, causing 2 km of deepening, followed by 2 km of thinning of the atmospheric boundary layer ahead of the fire. Future research with non-stationary fires is required to quantify the impact of the modified thermodynamics and wind patterns on fire behaviour.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/acp-26-13531-2026 eISSN: 1680-7324 eng

oai:publications.copernicus.org:acp131590 2026-09-25 acp

Pettersson, Susanne M. Azar, Christian Johansson, Daniel J. A. One possibility for reducing the climate impact of aviation is to transition to aircraft powered by hydrogen combustion. Hydrogen combustion leads to zero CO₂ exhaust emissions and represents a potential major step toward reduced climate impact, although the non-CO₂ effects (primarily contrail cirrus) remain uncertain. In this study, we simulate the climate impact, in terms of energy forcing, of contrail cirrus from hydrogen combustion aviation, using a modified version of the Contrail Cirrus Prediction model (CoCiP).

With no soot in the exhaust, contrail ice particles mainly form on ambient aerosols entrained into the plume and on lubrication oil droplets in the exhaust. The formation of ice particles is modelled using an emulator developed from a theoretically based microphysical contrail formation model.

Following the Schmidt-Appleman criterion, hydrogen combustion enables contrail formation at lower altitudes and higher temperatures than fossil jet fuel. However, we find a significant reduction in contrail energy forcing. This result holds across a wide range of assumptions, with a global average reduction of about 66 % using our base case assumptions on ambient aerosols, lubrication oil properties, droplet size distribution, emission index and energy efficiency of hydrogen aircraft. We conclude that hydrogen aircraft not only eliminate CO₂ emissions in the exhaust, but may also reduce the climate impact of contrail cirrus, depending on engine design for lubrication oil handling. However, we acknowledge that the modelling approach has limitations and uncertainties. Before firm conclusions can be drawn about the contrail cirrus effects of hydrogen-combustion aircraft, further studies are needed. These should include more realistic hydrogen aircraft models, alternative meteorological and microphysical models, and analyses of real-world flight patterns. In particular, measurements of lubrication-oil emissions from hydrogen aircraft under cruise conditions, as well as measurements of ice crystal number concentrations in hydrogen-aircraft contrails, would be valuable for constraining the present analysis.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/acp-26-13485-2026 eISSN: 1680-7324 eng

oai:publications.copernicus.org:acp129418 2026-09-25 acp

Farrell, Sara L. Rasool, Quazi Z. Pye, Havala O. T. Zhang, Yue Li, Ying Chen, Yuzhi Wang, Chi-Tsan Zhang, Haofei Schmedding, Ryan Shiraiwa, Manabu Green, Jaime Budisulistiorini, Sri H. Jimenez, Jose L. Hu, Weiwei Surratt, Jason D. Vizuete, William Aerosol particles contain complex mixtures of polar and non-polar species that can undergo organic-inorganic phase separation. In phase-separated aerosol particles, the phase state of the outer organic coating can modulate heterogeneous chemistry. Heterogeneous chemistry leading to isoprene epoxydiol (IEPOX)-derived secondary organic aerosol (IEPOX-SOA) is encoded in the Community Multiscale Air Quality (CMAQ) model and has been the focus of previous aerosol phase separation and phase state work. In a previous study, a constant ratio of water in the organic coating (w_s) was assumed in modeling phase separation and state. Recent studies, however, have highlighted w_s as an important modulator of phase state. This work uses a later CMAQ version (version 5.3.2) with capabilities to model dynamic water uptake to the organic coating – to better predict w_s and its impact on the organic coating phase state. In addition, new parameterizations for estimating organic aerosol phase state were encoded into CMAQ, and were compared with respect to their impacts on phase state and IEPOX-SOA predictions. These evaluations were completed simulating a summertime episode over the continental United States. Simulated diurnal profiles of aerosol phase state agreed within one standard deviation of observationally-derived field measurements. The implementation of phase separation and phase state parameterizations resulted in times and grid cells where IEPOX reactive uptake is completely suppressed. While modelled positive bias in 2-methyltetrol concentrations were decreased with phase separation and phase state updates, modelled methyltetrol sulfates and total IEPOX-SOA concentrations further underpredicted field observations in comparison to Base CMAQ.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/acp-26-13557-2026 eISSN: 1680-7324 eng

oai:publications.copernicus.org:egusphere146592 2026-09-25 egusphere

Das, Sampa Colarco, Peter R. Case, Parker Steenrod, Stephen Oman, Luke D. Taha, Ghassan R_eff) of ~ 0.30 µm, consistent with in-situ and lidar observations. Based on these results and offline Mie-theory calculations, we derive an observationally constrained configuration (R_eff = 0.30 µm, σ = 1.2, with moderated near-UV absorption) for the computationally efficient GOCART-2G bulk aerosol module. Compared to the finer-mode baseline, the updated configuration significantly improves simulated aerosol extinction and Ångström Exponent, bringing the plume's spatial distribution and longevity into closer agreement with SAGE-III/ISS and OMPS-LP satellite records. Furthermore, pairing the larger particle size with observationally constrained absorption moderates excessive shortwave radiative heating, enabling more realistic large-scale transport. The larger particle size assumption also reduces the available aerosol Surface Area Density (SAD) by more than a factor of three. Our findings highlight a critical sensitivity to particle size assumptions in simulating large pyroCb events, demonstrating that constraining this property is essential for accurately assessing the plume's radiative impact and its role in heterogeneous chemistry.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5642 eISSN: eng

oai:publications.copernicus.org:egusphere145596 2026-09-25 egusphere

Oestreicher, Nicolas Denzinger, Florian Manconi, Andrea to multitemporal terrain models. Our approach has been developed to overcome the DIC limitation in the vertical component
of the displacement field when horizontal shifts are larger than the grid sampling. To validate the performance, we applied
the approach to two terrain models acquired over the Brienz/Brinzauls landslide, where surface displacements affect the entire
slope with heterogeneous amplitudes and directions. The comparison with in-situ measurements shows that DIC can accurately
retrieve horizontal and vertical displacements, providing a clear representation of the spatial extent of the mass movement, as
well as an accurate distinction of the internal landslide compartments. Our results are in good agreement with those obtained
using a state-of-the-art point correlation method, but require less preprocessing and computational effort. Thus, the proposed
DIC strategy can be considered as a valid alternative for measuring 3D surface displacements in scenarios where multitemporal
terrain models are available.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5055 eISSN: eng

oai:publications.copernicus.org:egusphere145758 2026-09-25 egusphere

Vural, Mehmet Sait 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5171 eISSN: eng

oai:publications.copernicus.org:egusphere146417 2026-09-25 egusphere

Wilcken, Klaus M. Fülöp, Réka-H. Simon, Krista Kotevski, Steve Codilean, Alexandru T. Rood, Anna H. Rood, Dylan H. 10Be and ²⁶Al analyses, we analysed a suite of liquid and quartz reference materials, together with duplicate preparations of unknown research samples. Comparison among these materials allows us to constrain uncertainties associated with AMS measurement, chemical extraction, and quartz purification, and to assess whether additional variability is introduced at successive stages of the analytical process. Samples were prepared in three chemistry laboratories at the Australian Nuclear Science and Technology Organisation (ANSTO), the University of Wollongong (UOW), and Imperial College London, and subsequently analysed by accelerator mass spectrometry (AMS) using the 6 MV SIRIUS accelerator at ANSTO. All three laboratories showed intra-laboratory variability below the routine 2% analytical uncertainty, while measured values were consistent with the nominal values of the reference materials. These results indicate that both methodological reproducibility and inter-laboratory variability are also within the analytical uncertainty, and provide no evidence for additional uncertainty associated with processing quartz relative to liquid reference materials. The implications for cosmogenic-nuclide research are that: (1) the reproducibility and precision of cosmogenic ¹⁰Be and ²⁶Al analyses are typically 2–3% when sufficient counting statistics are achieved; (2) at lower isotope concentrations, counting statistics and/or background corrections may limit the achievable measurement uncertainty, although the resulting variability remains consistent with the reported analytical precision; and (3) precision of approximately 1% is achievable for high-concentration liquid reference materials, as demonstrated by Be-KN-5-4 and Al-KN-4-3, but has not yet been demonstrated for quartz samples.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5512 eISSN: eng

oai:publications.copernicus.org:egusphere146335 2026-09-25 egusphere

Saporta, Paloma Pardini, Matteo Wilcox, Evan J. Boike, Julia Hajnsek, Irena 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5452 eISSN: eng

oai:publications.copernicus.org:egusphere146316 2026-09-25 egusphere

Li, Zhuomin Alvera-Azcárate, Aida Barth, Alexander Bensoussan, Nathaniel Guan, Lei Xu, Na in situ data as reference. The hourly in situ data from 3 sites located in/nearby distinct upwelling areas from the Gulf of Lion (Marseille-Toulon area). The results show that the reconstructed COCTS SST characterizes most SST cooling events caused by upwelling, but not as intense as the in situ SST. Second, to overcome this limitation, we propose a wind-informed cloud detection procedure that takes into account wind speed and direction in order to improve the classification of upwelling-influenced pixels. The COCTS SST obtained by this improved cloud mask is subsequently reconstructed using DINEOF. The improved reconstructed COCTS SST has higher consistency with the in situ SST in the upwelling area. The results show the difficulty of cloud masking in areas with strong upwelling events and that the improved reconstructed HY-1D/COCTS SST, enabled by wind-informed cloud detection, have the potential to accurately describe such events.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5436 eISSN: eng

oai:publications.copernicus.org:egusphere146180 2026-09-25 egusphere

Wang, Ye Wild, Oliver Hou, Xuewei Hossaini, Ryan 2) is under consideration as a green energy source for future low-carbon development pathways. However, assessment of the future climate impacts of large-scale H₂ use is currently limited by poor understanding of the dominant atmospheric removal process, the uptake of H₂ by microbial activity in soil. Here we implement a soil dry deposition scheme for H₂ in a global chemistry transport model and conduct a sensitivity analysis to quantify how uncertainties in soil parameters contribute to uncertainty in H₂ uptake. We find that soil moisture dominates the uncertainty (52 %), along with contributions from soil porosity (34 %) and the water threshold for biological activity (13 %). However, the sensitivity of uptake to soil moisture is strongly nonlinear, with increases in uptake with declining soil moisture where it is under biotic control and with increasing soil moisture where it is under diffusivity control. We show that soil uptake dominates the interannual variation in atmospheric H₂ abundance from 2010 to 2022, and the notable decrease in 2015, while enhanced atmospheric production drives the observed long-term increase. Our results suggest that both soil sink and source of H₂are affected by strong ENSO events driven by changes in soil moisture. Using output from 11 CMIP6 models, we project changes in H₂ soil uptake between 2015 and 2100 of −2.5 % to +7.9 % under SSP1-2.6 and +4.1 % to +20.4 % under SSP5-8.5, suggesting an increase in soil uptake under climate change associated with future changes in soil moisture.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5371 eISSN: eng

oai:publications.copernicus.org:egusphere146434 2026-09-25 egusphere

Rosier, Sebastian H. R. Gregov, Thomas Jouvet, Guillaume Vieli, Andreas -1 and a median flux-divergence error of 0.10 m yr^-1. In transient simulations of two real glacier systems that lie outside the training set, the emulator tracks reference simulation ice volume through a 500-year advance-retreat cycle with maximum errors below 6%. Crucially, we find that errors do not accumulate over time. Instead, velocity biases induce geometric changes that tend to counteract them, stabilising the coupled emulator–mass-conservation system. Taken together, our results show that the expensive part of higher-order ice flow can be paid for once during training and reused indefinitely: velocity is predicted in a single forward pass rather than solved for iteratively at every time step. Higher-order ice dynamics are therefore no longer the limiting cost in mountain-glacier modelling, and become practical in large regional and global projection ensembles.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5523 eISSN: eng

oai:publications.copernicus.org:egusphere146495 2026-09-25 egusphere

Racek, Ondřej Loche, Marco Hartvich, Filip Blahůt, Jan

This study investigates meteorologically driven rock slope surficial dynamics using high-resolution crack meter measurements of blocks ranging in volume from 0.3 to 150 m³ and environmental monitoring data collected from four instrumented sites in Czechia, Central Europe. Each site comprises unique geological and morphological conditions and is equipped with joint displacement sensors, a weather station, and an in-depth thermal probe. A total of twelve representative rock blocks were monitored across the sites, capturing both thermally driven and potentially gravitationally induced displacements.

We analysed multi-year time series data (≥2 years) to assess the relationships between joint movements and meteorological variables, including air temperature, in-depth rock temperature up to 3 m and rainfall. Statistical observations revealed distinct seasonal and diurnal cycles in joint dilation linked to thermal forcing. Moreover, several blocks exhibited signs of compound kinematics, with joint displacements influenced by thermal cycles, rainfall and irreversible gravitational destabilisation trends.

This study provides new insights into the temporal dynamics of rock slope instability in temperate climates. The observed thermal sensitivity highlights the importance of temperature variations in driving short-term reversible joint deformation and potentially contributing to progressive rock-slope destabilization. This study demonstrates the value of long-term, high-frequency monitoring for quantifying weather–rock mass interactions and supports the integration of kinematical interpretations into future monitoring system designs.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5565 eISSN: eng

oai:publications.copernicus.org:egusphere146577 2026-09-25 egusphere

Zhang, Xinyu Ding, Wenwu Meng, Xiangguang Li, Ying Liu, Yan Yuan, Yunbin Clock offset constitutes a major error source for Global Navigation Satellite System (GNSS) radio occultation (RO) products, particularly for stratospheric observations. The adoption of high-rate clock correction strategy can effectively mitigate clock offset induced errors. In this study, high-rate (1-s) undifferenced (UD) Low Earth Orbit (LEO) clock corrections are used to retrieve RO observations from the Fengyun-3E (FY-3E) satellite. The retrieval results are compared with those derived from the conventional 30-s clock correction scheme and the single-difference (SD) scheme currently adopted in the official data processing. The results demonstrate that the 1-s LEO clock correction scheme improves the overall quality of FY-3E RO retrievals. For bending angle, the most prominent improvements are found in the altitude range of 40-60 km. Globally, its systematic difference is roughly 3% smaller than that of the 30-s scheme and 1% smaller than the SD scheme. Such superiority further propagates downward to refractivity and dry temperature. For refractivity, the largest improvements are also found in the altitude range of 40-60 km with systematic differences for the 1-s UD scheme reduced by approximately 0.5% relative to the other two schemes. Standard deviations of the 1-s scheme remain consistently smaller across the complete height range. Standard deviations of dry temperature are also improved with standard deviations about 0.5% smaller than SD and 1% to 2% smaller than the 30-s scheme in the altitude range from 0-40 km. The results in this study demonstrate the capability of using 1-s clock correction scheme for further promoting Fengyun GNSS Occultation Sounder-II (GNOS-II) RO observations. The results here can provide support for future operational processing and archive reprocessing of all Fengyun GNSS occultation datasets.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5629 eISSN: eng

oai:publications.copernicus.org:egusphere146539 2026-09-25 egusphere

Aben, Ralf C. H. Knaap, Judith Hahn, Floris Wulterkens, Gerben Szalas-Motesiczky, Dániel Vissers, Emiel Engels, Arno Kleine, Arjan Fritz, Christian Kosten, Sarian 2 and CH₄ fluxes on multiple spatial scales. We describe the system’s design and test how empirically derived pressure and water vapour correction factors for the mid-cost CO₂ and CH₄ sensors increase the accuracy of reported concentrations and derived flux estimates. Here, we found a 17–37 % (CO₂) and 4–9 % (CH₄) higher mean flux estimate with pressure compensation during the 97-day measuring period. Compensation for water vapour resulted in much smaller differences (~1–2 % increase). Additionally, we calculated the mean CO₂ and CH₄ emission using high-frequency measurements during 97 days and simulated alternative measurement scenarios based on the full dataset and evaluated how well these ‘reference means’ could be approached by 1) single, daytime-only chamber flux measurements at daily to monthly intervals, and 2) short-term (2–3 days) automated chamber deployments every two–three weeks combined with machine learning-based gap-filling. Results of the simulation analysis showed that daytime-only measurements consistently and strongly underestimated the reference CO₂ mean. CH₄ emissions matched the reference mean well for daily, but not for monthly measurements (>90 % and ~23 % of simulations deviated <20 % of the reference mean, respectively). Short-term automated chamber campaigns, gap-filled using machine learning closely reproduced the CO₂ reference mean, with 89 % and 48 % of means being within ±20 % of the reference mean, for campaign intervals of two and three weeks, respectively. We conclude that high-frequency chamber measurements using mid-cost GHG analysers combined with empirical pressure corrections provide accurate emission estimates, a robust benchmark for evaluating reduced measurements strategies and gap-filling approaches, and potential for improved process-based understanding of GHG fluxes when combined with ancillary high-frequency measurements.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5600 eISSN: eng

oai:publications.copernicus.org:egusphere145533 2026-09-25 egusphere

Schindelholz, Valentin Cheaib, Aya Maufroy, Emeline Cornou, Cécile Pathier, Erwan 0 of the soil and sediment thickness H_bed). The Grenoble basin is known for its strong site effect that largely amplifies seismic waves emitted by earthquakes. We develop a specific processing protocol of the EGMS data to account for its high inherent noise (involving adequate spatial smoothing, and quality filtering of the measurements considered), and propose a statistical referencing so the developed models are fully independent of the EGMS dataset chosen as input. The models are applicable in Grenoble in high spatial resolution and result in over 100 000 new estimation points of the site conditions in the entire basin area. This work highlights the huge potential of satellite imagery to complement site-characterisation and microzonation studies specifically in urbanized valleys.]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-5011 eISSN: eng

oai:publications.copernicus.org:egusphere143060 2026-09-25 egusphere

Funke, Bernd Höpfner, Michael Bender, Stefan Errera, Quentin Grabowski, Udo Hoffmann, Alex Liu, Han-Li Pedatella, Nick M. Raspollini, Piera Ungermann, Jörn Sinnhuber, Björn-Martin

The Linear Performance Estimator (LPE) serves as a diagnostic tool that applies linear retrieval theory to quantify spatial resolution and retrieval uncertainties for atmospheric targets like temperature and trace gas concentrations. It features a novel extension to 2D tomographic retrievals, enabling the assessment of how instrument characteristics and uncertainties propagate into final Level-2 (L2) geophysical data products. The Fast Level-2 Simulator (FL2S) complements this by utilizing LPE-derived metrics to project high-resolution atmospheric model data fields onto a simulated CAIRT measurement grid, generating synthetic L2 data products that mimic the full retrieval chain. This allows for a streamlined assessment of how CAIRT’s spatial resolution and uncertainties affect specific scientific use cases.

Applying these tools to the CAIRT instrument characteristics, we demonstrate the mission’s capability to meet specified L2 and science performance requirements. The results confirm that the modular end-to-end simulation framework effectively translates instrument specifications into robust scientific performance metrics, providing a mature basis for possible future implementations of limb-imaging space missions. ]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-3881 eISSN: eng

oai:publications.copernicus.org:egusphere144487 2026-09-25 egusphere

Folch, Arnau Sandri, Laura Barsotti, Sara Aguiar, Simone Martínez Montesinos, Beatriz Guerrero, Alejandra Tierz, Pablo Pascual, Heribert Hernandez, Eva Mingari, Leonardo Costa, Antonio 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-4485 eISSN: eng

oai:publications.copernicus.org:egusphere142494 2026-09-25 egusphere

Yoo, Soojin Chang, Eun-Chul Lee, Johan 2026-09-25 Text application/pdf https://doi.org/10.5194/egusphere-2026-3472 eISSN: eng

oai:publications.copernicus.org:ard146363 2026-09-25 ard

Waheed, Anza Saturno, Jorge Malik, Arpit Rosahl, Johannes Pratzler, Sonja Nowak, Andreas 2026-09-25 Text application/pdf https://doi.org/10.5194/ar-2026-33 eISSN: 2940-3391 eng

oai:publications.copernicus.org:cp134506 2026-09-25 cp

Si, Weimin Herbert, Timothy Toggweiler, John R. Sea Surface Temperature reconstructions derived from alkenone biomarker (SST-alk) reveal a cooling trend in the North Atlantic during the late Holocene (the last 5000 years), contrary to the warming simulated by transient climate models driven by 20 ppm increase in greenhouse gas concentrations. In this study, we present new SST-alk time series from the inter-gyre region of the North Atlantic. Our results, together with existing data, indicate that late Holocene cooling is marked by an increasing zonal SST gradient across the mid-latitude North Atlantic, with more pronounced cooling in the west than in the east. Complementary planktonic foraminifera assemblage data, interpreted alongside other circulation proxies, suggest that a late Holocene reorganization of inter-gyre ocean circulation as a likely driver of this zonal asymmetry. Finally, we compare these proxy-based reconstructions with transient climate model simulations (TraCE-21k), and find that models do not reproduce the observed zonally asymmetric cooling and the inferred circulation changes. This misrepresentation of spatial and temporal variability likely explains the data-model discrepancy in the mid-latitude North Atlantic.

]]> 2026-09-25 Text application/pdf https://doi.org/10.5194/cp-22-1729-2026 eISSN: 1814-9332 eng

oai:publications.copernicus.org:bg140502 2026-09-24 bg

Gómez-Palacio, Andrés Marín-Suarez, Johana Pedroza-Ramos, Adriana Aranguren-Riaño, Nelson Northern Andean highland lakes support agriculture, water provision, and local livelihoods, but their bacterial communities remain insufficiently characterized. We conducted an exploratory survey of bacterial community composition and predicted functional potential in six water samples from four freshwater lakes in the Eastern Cordillera of Colombia: Fúquene, Tota, Calderona, and Colorado. Five samples collected in 2019 comprised the primary dataset, while a previously published Tota sample collected in December 2018 was reprocessed as a historical reference. Bacterial communities were characterized using 16S rRNA gene amplicon sequencing, and functional profiles were inferred using PICRUSt2. After sequence processing and taxonomic filtering, 3153 amplicon sequence variants were retained. Actinobacteria, Proteobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia were the predominant bacterial phyla. Coverage-standardized richness and diversity varied descriptively among samples, with Colorado showing the lowest estimated ASV richness. Taxonomic composition and Bray–Curtis dissimilarities also varied among samples, reflecting differences in dominant bacterial groups. Mycobacterium-assigned ASVs were detected in Fúquene and Tota, Leptospira-assigned ASVs occurred in these same lakes at relative abundances of 0.01 %–0.36 %, and Legionella-assigned ASVs occurred in all six samples at 0.11 %–4.60 %. These genus-level assignments do not establish pathogenic species, viability, transmission, or risks to aquatic animals or humans. PICRUSt2 predicted variation in functional profiles, including pathways associated with naphthalene degradation, bacterial chemotaxis, biofilm formation, bacterial secretion systems, and pyrimidine and folate metabolism. Bray–Curtis ordination of predicted pathway profiles showed sample-level separation, and weighted NSTI values ranged from 0.160 to 0.181. These predictions represent inferred genomic potential rather than direct evidence of gene presence, expression, or metabolic activity. Because sampling was limited and unbalanced and lacked concurrent environmental measurements, the observed patterns cannot be attributed to specific environmental drivers. This study provides an initial descriptive baseline for bacterial communities in four Colombian Andean lakes and identifies patterns for evaluation through replicated sampling, physicochemical measurements, metagenomics, and targeted validation.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/bg-23-6725-2026 eISSN: 1726-4189 eng

oai:publications.copernicus.org:bg140085 2026-09-24 bg

Chénier, Noémy Magyar, Paul M. Zopfi, Jakob Frey, Claudia Kuhn, Thomas Lehmann, Moritz F. Mohn, Joachim Nitrous oxide (N₂O) isotopocules provide key insights into microbial nitrogen cycling, but their interpretation requires well-constrained values for both oxygen isotope signatures (δ¹⁸O–N₂O) and intramolecular ¹⁵N site preference (SP) associated with N₂O production pathways. Site preference is widely used to distinguish N₂O formation pathways because bacterial denitrification is generally assumed to yield SP values near 0 ‰ through canonical NorB-mediated NO reduction. However, the extent to which SP remains stable across physiological states and changing NO reduction pathways remains poorly constrained. Likewise, interpretation of δ¹⁸O–N₂O associated with denitrification requires understanding the relative contributions of branching kinetic isotope effects and oxygen atom exchange between nitrite and water during N₂O formation.

Here, we investigated N₂O isotopic signatures during denitrification by Pseudomonas aureofaciens (NirK-bearing) and Pseudomonas chlororaphis (NirS-bearing) under active-growth and resuspension conditions using quantum cascade laser absorption spectroscopy (QCLAS) and isotope ratio mass spectrometry (IRMS). SP tracked canonical NorB-mediated NO reduction but transiently increased above +10 ‰ during early N₂O production, suggesting temporary activity of alternative NO reductases. These dynamics were only resolved through continuous QCLAS measurements, highlighting the importance of time-resolved isotopic observations. While SP remains a useful indicator of NO reduction mechanisms, these results show that even within denitrification, shifts between NO reduction pathways may lead to variable SP signatures.

In parallel, we quantified oxygen atom exchange between nitrite and water using incubations prepared in natural-abundance and ¹⁸O-enriched water. Contrary to expectations from denitrifier-method studies, P. aureofaciens exhibited substantial and highly variable oxygen-atom exchange (38 %–100 %), far exceeding previously reported values (<9 %). In contrast, P. chlororaphis showed consistently high but less variable exchange (∼ 66 %). Resuspension experiments reproduced the characteristic low- and high-exchange behavior reported for these strains under denitrifier-method conditions, demonstrating that these exchange values are specific to the methodological framework and not representative of actively growing systems. These results show that oxygen atom exchange is not governed solely by nitrite reductase identity (NirS vs. NirK) but is strongly modulated by physiological state and metabolic context, including active growth versus stationary-phase resuspension and differences in nitrite turnover. As a result, δ¹⁸O–N₂O cannot be interpreted as a fixed tracer of denitrification pathways outside the constrained conditions of the denitrifier method.

Together, these findings suggest that denitrifying bacteria may generate N₂O with a broader range of δ¹⁸O–N₂O and SP than previously assumed. This calls for a reassessment of N₂O isotopocule interpretations and emphasizes the need to integrate isotopic measurements with physiological and biochemical constraints.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/bg-23-6705-2026 eISSN: 1726-4189 eng

oai:publications.copernicus.org:bg139325 2026-09-24 bg

Jiang, Jize Winkel, Lenny H. E. Wüst-Galley, Chloé Bretscher, Daniel Necpalova, Magdalena Stenke, Andrea Six, Johan Nitrogen (N) is essential for agricultural productivity, but excessive N inputs result in substantial losses to the environment. Conducting N assessments at national scales is challenging because observational data are limited, especially over long time periods. Here we compiled detailed datasets and performed high-resolution biogeochemical modelling to quantify N budgets for Switzerland's diverse agricultural ecosystems over four decades, with a focus on croplands and grasslands (i.e., permanent managed meadows used for livestock feed). Between the 1980s and the 2010s, N use efficiency improved from 47 % to 57 % in croplands and from 63 % to 71 % in grasslands, while losses through leaching and gas emissions decreased by 24 % in croplands and 4 % in grasslands. These improvements are closely linked to the implementation of national-scale agri-environmental policies that reduced fertilizer use in the 1990s. However, despite increased efficiency, cropland soils experienced substantial N depletion between 1995 and 2011 (−23

kg N {ha}^{- 1} {yr}^{- 1}

) in croplands. Our results demonstrate that policy reforms have improved agricultural system functioning and reduced losses, but also reveal risks associated with unbalanced soil N, underscoring the need for integrated N management for sustainable agriculture.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/bg-23-6741-2026 eISSN: 1726-4189 eng

oai:publications.copernicus.org:egusphere144747 2026-09-24 egusphere

Junnaedhi, I Dewa G. A. Arkan, Muhammad Muzasyaroh, An Nur A. Nugraha, Dwina Fitriani, Rachmy Abdillah, Muhammad R. Suwarman, Rusmawan Sukendra, Sukendra Varquez, Alvin C. G. Inagaki, Atsushi Kanda, Manabu Climate change and rapid urbanization have increased the need for dense air temperature and humidity monitoring networks in tropical cities. Although low-cost sensors are widely available, the cost of radiation shields remains a major barrier to large-scale deployment. This study presents a low-cost horizontal tube radiation shield (H-Tube) constructed from commercially available pipes and fittings combined with a small number of 3D-printed components. Two versions were developed: a bright-annealed stainless-steel shield (H-Tube_SS) and a PVC shield covered with aluminum foil (H-Tube_PVC). Material costs were approximately USD 25 and USD 11, respectively, making them about 8 and 18 times less expensive than typical commercial radiation shields (>USD 200).

Performance was evaluated through comparative field experiments in a tropical urban environment in Bandung, Indonesia, using identical Vaisala HMP155A temperature-humidity probes. Measurements from the H-Tube were compared against a Cotton Region Shelter (CRS) reference and two commercial radiation shields: a multiplate (MP) shield and a vertical tube (V-Tube) shield. Under non-aspirated conditions, daytime temperature biases exceeded 4 °C and relative humidity biases exceeded 15% during periods of strong net radiation. In contrast, aspirated operation substantially improved performance, with temperature biases generally remaining within ±1 °C and relative humidity biases within ±5%, comparable to those of the commercial MP and V-Tube shields. The aspirated H-Tube_SS achieved a temperature RMSE of 0.49 °C relative to the CRS, comparable to the MP shield (0.53 °C) and slightly lower than the H-Tube_PVC (0.58 °C).

Simple bias-correction methods based on linear temperature regression and saturation-vapor-pressure adjustment for relative humidity were also developed and evaluated. For the H-Tube designs, temperature RMSE was reduced from 1.35-1.46 °C to approximately 0.56 °C under non-aspirated conditions and from 0.49-0.58 °C to 0.30-0.35 °C under aspirated conditions. Relative humidity RMSE was reduced to approximately 2.6-3.2% after correction. The correction methods also reduced temperature-measurement uncertainty, particularly for the non-aspirated configurations.

These results demonstrate that the aspirated H-Tube provides a practical, scalable, and low-cost alternative to commercial radiation shields for distributed temperature-humidity monitoring networks in tropical urban environments.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-4598 eISSN: eng

oai:publications.copernicus.org:egusphere143342 2026-09-24 egusphere

Campeol, Quentin Dupont, Nicolas Kaufmann, Olivier and disturbance maps have been produced. These include maps of the observed gravity, free-air anomaly, refined Bouguer anomaly, gravity disturbance, topography-free gravity disturbance.

This has involved the compilation and harmonisation of cross-border legacy and recent gravity data, combined with an homogeneous reprocessing and an interpolation using the equivalent source method. The legacy data come from the Belgian and French databases published by the ROB (Belgium) and BRGM (France) respectively, to which unpublished data from the Battaille 1967 campaign have been added after their retro-processing from Bouguer anomaly data. The new gravity data come from the recent MoreGeo 2019-2022 gravity acquisition campaign. This campaign covers an area of 820 km² with 3,784 gravity stations distributed along densely sampled lines and displays a RMSE range of 41.9 to 67.5 µgal after absolute gravity referencing. The gravimetric processing works presented in this paper rely on open-source Python libraries. These include an advanced total correction budget evaluation and topographic correction up to 167 km² in extent. The resulting maps are consistent with previous ones, in particular the strong correlation between the anomaly and the thickness of the Meso-Cenozoic deposits. It also shows new anomalies that may be due to deep-seated structures. It will be used as a basis for modelling the geothermal reservoir, provided that the effect of the Meso-Cenozoic deposits is accounted for.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-3978 eISSN: eng

oai:publications.copernicus.org:egusphere145953 2026-09-24 egusphere

Aanderen, Victor Quiquet, Aurélien Dumas, Christophe Michel, Elisabeth Parrenin, Frederic Ritz, Catherine Jiguet-Covex, Kévin The ice core extracted as part of the Beyond EPICA project is expected to provide the longest continuous climate record, reaching back at least 1.2 million years. However, the hypothesis that Dome C has remained stable over several glacial-interglacial cycles, which is a prerequisite for establishing a reliable age-depth relationship, remains unverified. Using the GRISLI2.0 ice sheet model, we perform an ensemble of 5 high-resolution nested simulations at 10 km × 10 km resolution to track the evolution of Dome C position over the past 800,000 years. Our results show that Dome C undergoes substantial displacements over time, strongly controlled by grounding line dynamics in the Aurora Subglacial Basin. Using a 1D ice flow model, we further demonstrate that these dome migrations can introduce age errors of several tens of thousands of years in the age-depth relationship, with the largest uncertainties affecting the oldest and deepest ice, precisely where the Beyond EPICA record is most critical.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5288 eISSN: eng

oai:publications.copernicus.org:egusphere146527 2026-09-24 egusphere

Hrachowitz, Markus Kaitna, Roland 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5589 eISSN: eng

oai:publications.copernicus.org:egusphere146466 2026-09-24 egusphere

Usman, Muhammad −1 on Gulf mascon cells, and the two mascon products diverge by 10–15 cm after 2021. Using instead the global barystatic rate (2.1 mm yr⁻¹) and a steric trend of 0.3–0.9 mm yr⁻¹, 2.1–3.2 mm yr⁻¹ of the observed 5.2–5.6 mm yr⁻¹ rise — roughly two-fifths to just over half, depending on the end date (2002–2021 or 2002–2025) and the steric route — is accounted for by neither ocean-mass nor steric change. This implies a Gulf-mean manometric trend of order 4–5 mm yr⁻¹ that regional GRACE cannot independently confirm or refute; we weigh a dynamic, remotely forced origin against two alternatives in the Discussion. Gulf sea level rose in the year following each of the four strong positive Indian Ocean Dipole events of the record, consistent with remote forcing through the Strait of Hormuz.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5546 eISSN: eng

oai:publications.copernicus.org:egusphere145976 2026-09-24 egusphere

L. L. de Amorim, Felipe Feser, Frauke Weisse, Ralf 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5306 eISSN: eng

oai:publications.copernicus.org:egusphere146459 2026-09-24 egusphere

Moreno, Mateo Parente, Leandro Hein, Lars Bonannella, Carmelo Xu, Qin Isik, Mustafa Serkan Wibisana, Maulana Ikram Piccoli, Michelle Hengl, Tomislav F1 ≥ 0.94) and water bodies (F1 ≥ 0.85) performed best across both resolutions due to their high spectral distinctiveness and spatial coherence. Cropland classification was more accurate in the 30 m product (F1 = 0.81) than in the 10 m product (F1 = 0.72), as the 30~m GLAD GLCLUC backbone provides a stronger cropland signal. Macro-averaged F1 across all classes was effectively identical between 10 m (0.63) and 30 m (0.62), demonstrating that spatial resolution alone does not govern overall accuracy. The poorest performance was registered for sparsely vegetated ecosystems and inland wetlands. Urban ecosystems appear to be overestimated in the 30 m map. The datasets can be used for reporting on ecosystem extent and ecosystem services in ecosystem accounting. The biggest limitations of the GHLC are (1) that it is based on manual rules that may be subject to errors, and (2) that it relies on 24 independently derived external layers, each produced and maintained by separate research groups or agencies. If those external groups cease updating or maintaining their specific datasets, the corresponding GHLC rules cannot be applied, causing the classification system to degrade.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5540 eISSN: eng

oai:publications.copernicus.org:egusphere146409 2026-09-24 egusphere

Drüke, Markus Künzel, Alice Böhm, Uwe Castino, Fabiana Deutschländer, Thomas Fiedler, Anett Höschel, Ines Machui-Schwanitz, Grit Rauthe, Monika Schneider, Gerold Wichura, Bodo Here, we present SNOWRAS, a new gridded snow depth dataset for Germany covering extended winter seasons from 1950/51 to 2025/26. The dataset is based on daily snow depth observations from the extensive monitoring network of the Deutscher Wetterdienst (DWD), complemented by measurements from partner networks in Germany and neighboring countries. After quality control and data cleaning, the station observations were interpolated to a regular 1 × 1 km grid using an optimal interpolation scheme.
Based on this dataset, we derived and analyzed several snow-climatological indicators, including seasonal mean and maximum snow depth, the number of snow days, and the timing of the first and last days with seasonal snow cover. Across Germany, most indicators show a statistically significant decline over the past 75 years. The magnitude of these changes varies considerably with elevation: the largest decreases in snow depth and snow cover duration are found in lowland and mid-elevation regions, while these trends are generally weaker at higher elevations and are partly not statistically significant. SNOWRAS provides a spatially consistent, high-resolution dataset for monitoring snow conditions and investigating long-term changes in Germany’s snow climate. Together with complementary information, such as snow water equivalent, the dataset can also support hydrological modeling, assessments of water availability, and analyses of hydrological risks.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5507 eISSN: eng

oai:publications.copernicus.org:egusphere146289 2026-09-24 egusphere

Shapiro, Anna V. Foelsche, Ulrich Annalen des Physikalischen Centralobservatoriums' in Saint Petersburg to assess their potential for Eurasian climate analysis. We digitized monthly temperature and pressure data from printed tables and converted them into a machine-readable dataset, addressing challenges related to station metadata, spatial coverage, multilingual headings, historical station names, decimal notation, missing entries, and optical character recognition errors. Using selected stations, we construct monthly surface air temperature and pressure anomaly maps for 1877 and 1879 relative to station-specific monthly reference means based on the other available years within 1874-1894. The year 1877 falls within the major 1877-1878 global climate anomaly, while 1879 provides a contrasting case. The station-based anomaly maps show coherent spatial structures across large parts of Eurasia. In 1877, late-year positive pressure anomalies over central and eastern Eurasia are accompanied in December by widespread cold anomalies. In 1879, the maps show stronger regional contrasts and a markedly different December pressure pattern. Our results demonstrate that the Annalen observations are valuable not only as historical records, but also as quantitative data for studying nineteenth-century atmospheric variability.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5428 eISSN: eng

oai:publications.copernicus.org:egusphere146347 2026-09-24 egusphere

Meena, Sansar Raj 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5462 eISSN: eng

oai:publications.copernicus.org:egusphere145655 2026-09-24 egusphere

Touseef, Muhammad Chen, Lihua 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5097 eISSN: eng

oai:publications.copernicus.org:egusphere145684 2026-09-24 egusphere

Kray, Elisabeth N. Kilgour, Delaney B. Rogers, Martina N. Jernigan, Christopher M. Vermeuel, Michael P. Bertram, Timothy H. 2) and dimethyl sulfide (C₂H₆S, DMS). OCS is the largest continuous contributor to stratospheric sulfate aerosol and a key diagnostic for the photosynthetic uptake of carbon dioxide (CO₂). Despite its importance to the OCS budget, in situ measurements of CS₂ are extremely limited. Here, we describe a new technique for the simultaneous measurement of CS₂, OCS, and DMS utilizing O₂⁺ chemical ionization time-of-flight mass spectrometry (O₂⁺ CI-ToFMS). We highlight the utility of the measurement through the reanalysis of three distinct data sets taken in remote marine, remote continental, and urban environments. We report mean CS₂ mixing ratios for the Eastern North Atlantic (2.2 ppt) and Downtown Chicago, IL (9.5 ppt), while CS₂ was not detected in Northern Wisconsin. In the Eastern North Atlantic, CS₂ showed limited temporal variability during the summer. In Chicago, CS₂ was highly variable, with episodic large enhancements (>85 ppt) suggesting local, anthropogenic sources. Results of laboratory measurements and success in the quantification of field measurements suggest that primary and secondary O₂⁺ CI-ToFMS is suitable for simultaneous, in situ detection of CS₂ and OCS.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5120 eISSN: eng

oai:publications.copernicus.org:egusphere145802 2026-09-24 egusphere

Niida, Yasuhiro Okochi, Hiroshi Yoshida, Norihisa Tani, Yuto Sasai, Shunki Fujii, Yusuke Takenaka, Norimichi 2.5 fraction remains challenging. Conventional µFTIR imaging studies of atmospheric aerosol have generally targeted larger particles, and the reliability of library-matching scores at this smaller size range has not been systematically examined. We present a µFTIR-ATR imaging workflow that separates spectral processing for chemical identification from image processing for physical characterisation. For chemical identification, particle-level spectra were smoothed and evaluated through library matching combined with diagnostic-band interpretation. For physical characterisation, PCA-based image processing and blank-derived intensity thresholds defined particle boundaries for Feret-dimension measurement and morphological classification. We defined the TopHit ratio as the proportion of top-ranked library assignments agreeing with diagnostic-band interpretation within each maximum-correlation-coefficient (R_max) interval. Among 674 particles, this ratio rose from 41.1% at R_max = 0.4–0.5 to 96.0% at R_max = 0.8–0.9 and 100.0% at R_max = 0.9–1.0; a Richards growth model best described this relationship across four tested library/bin-width combinations. The workflow also enabled identification and measurement of an airborne polyethylene terephthalate particle collected in the PM_2.5 fraction, with an apparent minimum Feret dimension of 2.3 µm. To our knowledge, this is the first study to combine µFTIR-based polymer identification of an airborne PM_2.5 particle approaching 2 µm with explicit empirical calibration of spectral-matching confidence.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5191 eISSN: eng

oai:publications.copernicus.org:egusphere145776 2026-09-24 egusphere

Marcon-Henge, Lediane Peichl, Matthias Larmanou, Eric Graf, Alexander 2 measurements provide essential constraints for atmospheric modelling and carbon-budget estimates. Measurements made at tall towers, typically at heights of approximately 100m and above, are more representative of well-mixed atmospheric conditions than near-surface observations, however their spatial coverage is limited. Virtual Tall Tower (VTT) methods offer a potential approach to scale CO₂ mixing ratios from eddy-covariance stations, where measurements are made closer to the surface, typically 2–50m above ground, to tall-tower heights, thereby expanding the spatial coverage of the existing sparse atmospheric observation network. In this study, we evaluated the performance of an existing VTT approach
for estimating CO₂ mixing ratios from 35m to 150m at the combined ecosystem–atmosphere station at Svartberget, a forest-dominated site in northern Sweden. The dataset covered five years (2020–2024) of eddy-covariance fluxes, tall-tower CO₂ mixing-ratio measurements, and planetary boundary layer height from ERA5 reanalysis. The baseline VTT set-up estimated CO₂ mixing ratios with low bias (0.03 μmolmol⁻¹), low RMSE (0.75 μmolmol⁻¹), and a high squared Pearson correlation coefficient (r² = 0.99). The largest discrepancies between estimated and measured mixing ratios occurred under atmospheric conditions with weakened vertical mixing, particularly during winter months and in the early morning. Moreover, surface CO₂ flux, sensible heat flux, planetary boundary layer height, and displacement height were among the most influential variables in the approach, as perturbations in these variables led to changes in performance metrics. The underlying VTT assumption of well-mixed conditions is an important constraint that limits the applicability of the method under stable atmospheric conditions, such as during night-time and cold days. In addition, well-calibrated eddy- covariance CO₂ mixing-ratio measurements are crucial for good VTT performance. Therefore, although the VTT approach is a promising tool for expanding atmospheric CO₂ mixing-ratio information from near-surface measurements, further investigations across different sites and environmental conditions are needed to improve and generalize the approach.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/egusphere-2026-5181 eISSN: eng

oai:publications.copernicus.org:essd139032 2026-09-24 essd

Luppichini, Marco Comiti, Francesco Andreoli, Andrea Aldighieri, Barbara Billi, Paolo Bollati, Irene Maria Brenna, Andrea Chirici, Diletta Ciavola, Paolo Cilli, Silvia Donnini, Marco Francalanci, Simona Innocenti, Lorenzo Longoni, Laura Mao, Luca Marchesini, Ivan Murgia, Ilenia Pellegrini, Giacomo Penna, Daniele Picco, Lorenzo Rainato, Riccardo Schippa, Leonardo Solari, Luca Tronti, Gianluca Testa, Bruno Verdone, Matteo Bini, Monica Fluvial sediment transport plays a key role in geomorphological and hydrological processes, influencing river morphology, watershed and coastal sediment balances, and the environmental response to climatic and anthropogenic changes. In Italy, the availability of homogeneous and long-term data is strongly limited due to the discontinuity of monitoring activities and the fragmentation of existing sources. This study presents the development of a relational database and web application specifically designed for the collection, storage, and consultation of sediment transport data, aimed at integrating and enhancing heterogeneous datasets from both historical and contemporary monitoring networks: the Italian Fluvial Sediment Transport Database (ITASED). The database architecture, developed in PostgreSQL with the PostGIS extension, enables a direct link between observational data and their associated geographical, instrumental, and methodological metadata, ensuring traceability, interoperability, and the possibility to perform multi-temporal analyses. The web interface, built using open-source technologies, allows controlled data entry and interactive data exploration through maps, tables, and export functions. Analysis of the archived datasets highlights strong instrumental, temporal, and spatial heterogeneity: some physical-chemical parameters (e.g., pH and electrical conductivity) show standardized measurement protocols, whereas sediment transport variables exhibit high methodological variability. Time series range from sub-daily to annual observations, with denser coverage in northern Italian basins (e.g., Po, Adige, Piave, Tagliamento) since 1924. Despite these inconsistencies, integration within a unified relational framework enhances the value of a largely underused data heritage. The experience gained through this project enabled the identification of both the limitations and the potential of Italy's sediment monitoring system, providing operational guidance for methodological standardization, metadata improvement, and data harmonization at the national scale. The ITASED represents a concrete step toward establishing a shared sedimentological archive that supports scientific research, environmental management, and sustainable river basin planning. The dataset is publicly available on Zenodo at https://doi.org/10.5281/zenodo.18799025 (Luppichini et al., 2026).

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/essd-18-7021-2026 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essdd143427 2026-09-24 essdd

Wu, Peiwen Su, Yang Wang, Mengru Yang, Xiaomei Rillig, Matthias C. Wang, Xiahui Liu, Ruiping Ye, Su Zhou, Lianqing Shi, Zhou Chen, Songchao 2026-09-24 Text application/pdf https://doi.org/10.5194/essd-2026-536 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essdd145620 2026-09-24 essdd

Yu, Han Wu, Mousong Yin, Dongjie Ran, Youhua Yi, Yonghong -1, whereas autumn freezing was delayed by 2.22-3.24 d decade^-1 across the three soil depths. By combining long temporal coverage, daily resolution, and multi-depth representation, FT-KGML provides a new resource for cryospheric, hydrological, ecological, and land-surface modelling communities investigating frozen-ground variability, subsurface seasonality, and long-term environmental change. The dataset is available at https://doi.org/10.5281/zenodo.22019944 (Yu and Wu, 2026).]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/essd-2026-683 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essdd146314 2026-09-24 essdd

Fang, Feifan Yang, Yifeng Jin, Peng Zhou, Binzhen https://doi.org/10.57760/sciencedb.011ul; Fang et al., 2026).]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/essd-2026-737 eISSN: 1866-3516 eng

oai:publications.copernicus.org:essdd146400 2026-09-24 essdd

Wang, Rong Ren, Jian Diekmann, Bernhard

The archive preserves 555 chronology-control rows with their provenance, material roles, and admission decisions. The 18 verified formal model-input files contain 285 rows representing 282 dated-depth clusters or legacy calendar-age nodes. Twenty-eight constraints misassigned to surface chronology during an earlier stage of this compilation are retained with their material-role and exclusion records, allowing users to inspect or revise the admission decisions. The primary precision descriptor is the median width of the pointwise 95 % posterior age interval within each dated interval. Among 14 inventory rows assigned a derived convenience bin, this statistic ranges from 677 to 2765 yr, with a median of approximately 1100 yr. Sampling diagnostics are reported at all evaluation depths. Independent reruns of four preselected records changed this continuous statistic by at most 6.64 yr, although one boundary-adjacent record crossed a derived-bin boundary.

Posterior precision is conditional on calibration, the reservoir correction and its adopted date-level uncertainty, input representation, and the modelling protocol; it does not establish absolute chronological accuracy. The adopted reservoir corrections are based on modern observations, whereas deglacial reservoir histories remain incompletely constrained. The release combines age tables, audited inputs, cluster definitions, diagnostics, per-record JSON/CSV packages, source references, and implementation records to support reuse and alternative chronological modelling. Executed model inputs are preserved, but recovery of the full source-to-prepared transformation chain is incomplete. The data are deposited at PANGAEA under https://doi.pangaea.de/10.1594/PANGAEA.996868.]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/essd-2026-742 eISSN: 1866-3516 eng

oai:publications.copernicus.org:gh131001 2026-09-24 gh

Runkel, Simon The article examines the terms earth, globe and world as central ciphers of geographical thinking and places them in a genealogy of the history of ideas and science. The focus is on the current boom in planetary thinking, which is fanned out into two currents: on the one hand in (earth) system-theoretical totality, on the other hand in post-humanist perspectives on co-existence. In both discourses, a new Copernican turn is claimed, whose metaphorological content, however, points to a continuation of post-Copernican ambivalence. Based on Hans Blumenberg's metaphorology, it is shown how planetary semantics oscillates between epistemic upheaval and anthropocentric self-assertion (Selbstbehauptung). The article is intended as a plea for a stronger reception of humanities thinking styles in geography. Here, metaphorology proves to be an approach to the critical reflection of disciplinary world and self-relations under the sign of planetarism. The euphoric welcome of planetary thinking in geography and the pleas for a new Copernican turn are evidence of the unbroken discursive power of this metaphor.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/gh-81-517-2026 eISSN: 2194-8798 eng

oai:publications.copernicus.org:esd132460 2026-09-24 esd

Banville, Pierre Etienne MacIsaac, Alexander J. Zickfeld, Kirsten Forestation, including reforestation, afforestation, and forest restoration, is prevalent in net-zero climate strategies due to the large carbon sequestration potential of forests. In addition to capturing carbon, forestation has biogeophysical effects that can influence surface temperatures locally (local effects), and at distant locations (non-local effects). Biogeophysical effects may offset the cooling benefits of carbon sequestration, hence requiring a robust understanding of their mechanisms to adequately integrate forestation into climate mitigation strategies. Yet, the role of ocean dynamics, such as ocean circulation, ocean-atmosphere interactions, and ocean-sea ice interactions in mediating the non-local effects of forestation remains underexplored. In this study, we investigate the impact of ocean dynamics on the magnitude and geographic patterns of the non-local biogeophysical effects of large-scale reforestation, with the exclusion of cloud feedbacks, over a multi-century timescale using the University of Victoria Earth System Climate Model. We conduct multi-century paired global reforestation simulations, with the first set of simulations using a dynamic ocean and the second set using prescribed sea surface temperatures. We separate local from non-local effects using the checkerboard approach. Our results show that non-local warming effects are of much greater magnitude and encompass a greater geographic area, particularly at high latitudes, when ocean dynamics are considered. Moreover, this study shows that ocean dynamics introduce a lag in the non-local effects, leading to a continued increase in non-local warming even after the local effects have stabilized. This committed non-local warming is driven by the thermal inertia of the ocean, which sustains a gradual long-term increase in sea surface temperatures, combined with amplifying climate feedbacks. Decision-making frameworks must therefore consider the complete Earth system response to forestation over a sufficiently long timeframe to account for the committed non-local warming.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/esd-17-1315-2026 eISSN: 2190-4987 eng

oai:publications.copernicus.org:hess135606 2026-09-24 hess

Asfaw, Binyam Workeye Maksud, Siam Fuka, Daniel R. Collick, Amy S. White, Robin R. Easton, Zachary M. Watershed streamflow is often the focus of hydrological model calibration and evaluation, despite other potential objectives, including water quality management, flood protection, or agricultural management. When hydrological models are calibrated on streamflow, intermediate processes such as those affecting soil-moisture are not necessarily well represented. This research evaluated whether calibration using downscaled and bias-corrected satellite soil-moisture improves prediction of field-scale soil-moisture relative to conventional streamflow-based calibration. In this work, downscaled satellite soil-moisture and streamflow data are used to calibrate a soil and water assessment tool – variable source area model initialized using a terrain informed process to create hydrologic response units. In-situ soil-moisture measurements at 25 locations across a 4.2-ha mixed-grass pasture located in southwestern Virginia were used to estimate field-scale average soil-moisture variability for model evaluation. Leveraging downscaled satellite soil-moisture data substantially improved estimation of temporal soil-moisture variability without affecting the model streamflow performance. The multi-objective calibration using streamflow and satellite soil-moisture improved soil-moisture performance while maintaining streamflow performance comparable to streamflow-only calibration. These results demonstrate the potential for satellite soil-moisture–informed calibration to improve internal hydrologic state estimation in small, saturation excess watersheds. Furthermore, these results highlight the importance of coupling statistical performance gains with evaluation of hydrologic realism when extending such approaches to broader modeling applications.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/hess-30-5999-2026 eISSN: 1607-7938 eng

oai:publications.copernicus.org:hess138230 2026-09-24 hess

Khedhaouiria, Dikraa Gasset, Nicolas Fortin, Vincent Dimitrijevic, Milena Bulat, Maxim Wang, Xihong The Canadian Surface Reanalysis (CaSR) includes an offline, high-resolution gridded total precipitation reanalysis designed to provide accurate estimates across North America. This product, referred to as CaPA-24h, builds on the Canadian Precipitation Analysis (CaPA) system of Environment and Climate Change Canada (ECCC). It combines a dense network of daily surface observations with a background field from the CaSR dynamical component, using updated quality-control and assimilation procedures to filter spurious observations. This study evaluates the CaPA-24h fields produced in CaSR v3.2, together with their background field, and compares them with the previous version (v2.1) as well as with two independent datasets, ERA5-Land and PRISM. Results show substantial improvements in v3.2, particularly in data-sparse regions, with an enhanced representation of precipitation events of different intensities. Compared to ERA5-Land, CaPA-24h v3.2 provides more accurate seasonal and regional precipitation patterns, while evaluations against PRISM confirm this improved performance. However, biases persist in southern and western mountainous areas, especially for orographic precipitation. A first-time assessment of the hourly disaggregated product reveals limitations in the diurnal cycle representation, indicating the need for refined disaggregation methods and background field generation. Overall, CaPA-24h v3.2 delivers a reliable and well-established gridded precipitation dataset, offering a valuable resource for hydrological, climatological, and impact studies across North America.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/hess-30-5971-2026 eISSN: 1607-7938 eng

oai:publications.copernicus.org:gmd134208 2026-09-24 gmd

Macé, Loïc Vandenbulcke, Luc Brankart, Jean-Michel Grailet, Jean-François Brasseur, Pierre Grégoire, Marilaure In this paper, we propose a three-stream ocean radiative transfer module as an extension of the Nucleus for European Modelling of the Ocean (NEMO). This module solves in-water irradiance fields in 1D water columns, discriminating between two downward streams, direct and scattered, and a backscattered upward stream. The module solves 33 wavebands between 250 and 4000 nm, with a resolution of 25 nm in the visible range. The sea surface reflectance is also calculated as a model output, based on the ratio between the upward and downward irradiances at the air-sea interface. We also use a feedback loop towards the computation of temperature in the NEMO model, made optional with this module. It also includes a stochastic version in which the inherent optical properties of the major optically active components of seawater can be perturbed. This mode is meant to account for uncertainty in the modelling of marine optics. This module can be plugged into any NEMO configuration, with the computation of optical properties driven either by a coupled biogeochemical model or directly forced into the radiative transfer module.

We apply this module in a test case for the Black Sea, within the NEMO framework and coupled to the Biogeochemical Model for Hypoxic and Benthic Influenced areas (BAMHBI). We find that substituting the existing radiative transfer scheme with our model unlocks the ability to simulate radiometric variables that can be compared more directly to observations, both in situ and from remote-sensing. We also find that using irradiances to compute the temperature and scalar irradiance that is available to phytoplankton in the coupled model maintains consistency in the calculation of physical and biogeochemical variables. The simulation of variables such as temperature or chlorophyll concentration is maintained, while enabling additional capabilities in the model with the simulation of radiometric quantities.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/gmd-19-9077-2026 eISSN: 1991-9603 eng

oai:publications.copernicus.org:gmd132287 2026-09-24 gmd

Sloughter, Trevor Nicholls, Zebedee Tang, Gang Kleinen, Thomas Zhang, Zhen Rogelj, Joeri Literature estimates of natural methane emissions, particularly from wetlands, have a wide range of uncertainty. Meanwhile, few Earth System Models (ESMs) explicitly model wetlands as a potential source of methane. As a result, Simple Climate Models that aim to emulate the behaviour of ESMs have little to constrain their present and future contributions. MAGICC, as of version 7.5.3, fixed natural methane concentrations as constant after the historical period. Two studies that model wetland methane emissions over the 21st century both find a relationship between those emissions and global temperature, though disagree on the extent of this temperature sensitivity. An updated version of MAGICC has been created that uses this evidence to include a linearised representation of the relationship between wetland methane emissions and global temperature. The temperature-sensitivity parameter in this relationship has been parametrised in a way such that its distribution encompasses the uncertainty in both modelling literature and carbon budget studies, reflecting the currently high degree of uncertainty in wetland emissions. Our results show how incorporating a temperature feedback in methane emissions leads to both higher temperature projections for all scenarios used here, and a widening of the uncertainty in global temperature response.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/gmd-19-9063-2026 eISSN: 1991-9603 eng

oai:publications.copernicus.org:gmd131805 2026-09-24 gmd

Li, Wanting Zhou, Linyi Wu, Xianghua Guan, Yuanhong Guo, Yuanhao Chen, Kun Huang, Weiqi Zhao, Wenqian Accurate prediction of road surface temperature (RST) is essential for proactive winter road maintenance and traffic safety management. However, existing approaches – ranging from physics-based models to data-driven methods – either require detailed pavement thermal parameters that are rarely available at operational road meteorological stations, or lack the capacity to simultaneously exploit local meteorological analogues and long-range temporal dependencies in an interpretable ensemble framework. This study proposes the Improved LSTMs Ensemble with Stacking (ILES) framework, which integrates two base learners with partially complementary predictive characteristics within a stacking ensemble employing out-of-fold cross-validation. The first base learner, KNN-LSTM, augments sequential modelling with similarity-based retrieval of historically analogous meteorological states to capture locally recurrent patterns. The second, BiLSTM-MHA, combines bidirectional recurrent processing with multi-head self-attention to extract long-range temporal dependencies across a 24 h input window. Moreover, a Bayesian Ridge Regression meta-learner fuses the base-learner outputs through Evidence Maximization, yielding probabilistic forecasts with closed-form posterior predictive uncertainty at the ensemble combination layer. The framework is trained and evaluated on four consecutive winter seasons (December 2020 to February 2024) of road meteorological observations from station M9393 in the northwest inland plain of Jiangsu Province, China. Results indicate that ILES achieves lower prediction errors in general than ten other models spanning persistence forecasting, traditional machine learning, and deep learning approaches, with R² reaching 0.993, 0.923, and 0.826 at 1, 3, and 6 h forecasting horizons, respectively. Among three input configurations evaluated, physics-motivated feature engineering incorporating the air–surface temperature gradient and multi-scale RST temporal tendencies outperforms both the station-only baseline and ERA5-Land reanalysis augmentation, indicating that domain-knowledge-guided feature construction provides a more effective and operationally practical input strategy at instrumented sites. SHAP-based interpretability analysis, stratified by temperature regime and diurnal cycle, confirms that the learned feature importance rankings are qualitatively consistent with the dominant drivers of RST evolution identified by surface energy balance theory. Multi-site generalization is further validated at two independent stations within the same temperate monsoon climate zone, confirming the transferability of the proposed framework across different road environments within this climate setting.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/gmd-19-9035-2026 eISSN: 1991-9603 eng

oai:publications.copernicus.org:gmd140589 2026-09-24 gmd

Béland, Martin Bonan, Gordon Kobayashi, Hideki Baldocchi, Dennis Forest canopy models are used to simulate biosphere–atmosphere coupling in global climate models, as well as the microclimate influences of forests at the stand scale. It has recently been shown that wood structures store significant heat following radiation absorption and impact air temperature diurnal patterns inside canopies. Yet, radiation absorption by woody stems is not fully considered in current models. Here we modify the radiative transfer component of the CanVeg2 multilayer canopy model to include radiation absorption by woody stems. We evaluate the model modifications by comparing estimates against a 3D ray tracing radiative transfer model parametrized using ground lidar measurements, and against tower observations of albedo in four broadleaf forests. We found a very good agreement between the 1D and 3D models, and a good agreement between models and observations. Our approach provides a tractable and computationally efficient implementation of radiation absorption by woody stems to calculate biomass heat storage in canopy models.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/gmd-19-9019-2026 eISSN: 1991-9603 eng

oai:publications.copernicus.org:tc137977 2026-09-24 tc

Aker, Tesse E. A. Kuipers Munneke, Peter Berg, Willem Jan Immerzeel, Walter W. Broeke, Michiel R. The firn layer regulates how an ice sheet responds to atmospheric climate change by modifying how changes in surface temperature, snow accumulation and ablation affect the ice-sheet mass balance. Firn properties are often simulated with a firn densification model. Prior studies have used a variety of time steps in the climate forcings of such firn models, ranging from 3 h to 1 d, 1-month, or even annual. The climate forcing time step impacts the creation of pore space by snow accumulation and the depletion of pore space by snowmelt and firn densification. To investigate this effect, we force the firn densification model IMAU-FDM with surface mass balance components and meteorological variables at different time steps for the Antarctic Peninsula and southern Greenland Ice Sheet. We show that the final modelled firn layer contains more pore space for larger forcing time steps, and that the magnitude of this effect depends on the climate regime. Locations with limited firn pore space due to seasonal melt, and regions with emerging firn aquifers, are most sensitive. The key in causing the differences in firn pore space is the presence or absence of a diurnal cycle in the input data. A climate forcing time step equal to or greater than a day allows for a non-physical coexistence of snowmelt and sub-zero surface temperatures, leading to immediate shallow refreezing of meltwater. Subsequent melting removes refrozen higher density firn rather than porous firn, reducing the amount of firn air that is lost through melting. Therefore, for locations experiencing surface melt, the decoupled temperature and snowmelt in the upper layers results in more firn air with a climate forcing time step equal to or greater than a day. We also found that model parameterizations can become unsuitable when applied outside the physical conditions or climate forcing time step on which they are based, leading to unrealistic firn densification behavior in the model. We argue that (1) firn models forced with surface mass balance terms and meteorological variables require a timestep small enough to capture at least the diurnal cycle, (2) parameterizations should be used in a way that is consistent with the development data.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/tc-20-5475-2026 eISSN: 1994-0424 eng

oai:publications.copernicus.org:wes135358 2026-09-24 wes

Cheung, Lawrence Mohan, Prakash Henry de Frahan, Marc T. Yalla, Gopal R. Hsieh, Alan Brown, Kenneth deVelder, Nathaniel Kaufman-Martin, Sam Day, Marc Sprague, Michael Despite many recent advances, modeling wind turbine wakes using semi-empirical and analytical models still faces challenges when dealing with more complicated situations involving wind shear, veer, atmospheric stratification, and wake superposition. To address these limitations, this study introduces a three-dimensional, parabolic Reynolds-averaged Navier–Stokes (RANS) k−ϵ formulation which includes an atmospheric boundary layer model and an actuator disk model for turbine wakes. The full three-dimensional solution for the velocity, temperature, and turbulence variables is efficiently solved through an alternating-direction implicit scheme that requires orders of magnitude fewer computational resources than traditional high-fidelity approaches, such as fully elliptic RANS or large-eddy simulations (LESs). The results of the parabolic RANS model are compared to the equivalent LES and semi-empirical wake models at different wind speeds under stable atmospheric conditions with veer and shear at a single TI level, as well as a convectively unstable-inflow case. For the single-turbine wake the RANS model was able to capture the wake deficit behavior, including the wake stretching and skewing that was observed in the LES. The distribution of the wake turbulence in the RANS model also agreed with results from the higher-fidelity simulations. In simulations of a two-turbine, directly waked configuration, the new RANS model was able to handle the wake superposition behavior without difficulty and also correctly modeled the corresponding increase in wake turbulence when compared to LES. A demonstration of the RANS model on a nine-turbine, three-row wind farm is shown and compared to LES, and comparisons with a semi-empirical veered Gaussian model are also discussed. The work in this study can be generalized in future investigations to handle additional wind conditions and more complex wind farm configurations.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/wes-11-3719-2026 eISSN: 2366-7451 eng

oai:publications.copernicus.org:wes133893 2026-09-24 wes

White, Craig Benifla, Victor Cândido, José Gato, Luís M. C. A structural and economic optimization framework applicable to floating semi-submersible platforms, demonstrated here for a 15 MW offshore wind design, is presented. A genetic algorithm was developed that can seek a multi-objective solution to minimize mass whilst respecting the constraints of loads acting upon the system. Statistical and machine learning methods are then employed to forecast short- and long-term costs of the platform under a range of exogenous data scenarios, selected to support and boost forecasting accuracy alongside a hybrid forecasting method. Steel mass was reduced from 3916 to 3273 t whilst respecting platform response constraints. The uncertainty in steel prices has the most significant impact on CAPEX, approximately EUR 150–200 million at the 1 GW level. Levelized cost of energy (LCoE) is calculated to gauge the technical and economic viability, with EUR 3–5 MW h⁻¹ variation across forecasts.

]]> 2026-09-24 Text application/pdf https://doi.org/10.5194/wes-11-3703-2026 eISSN: 2366-7451 eng 36616147