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1. Evaluation of sea-ice thickness from four reanalyses in the Antarctic Weddell Sea

   https://doi.org/10.5194/tc-15-31-2021  

   Shi, Qian; Yang, Qinghua; Mu, Longjiang; Wang, Jinfei; Massonnet, François; Mazloff, Matthew R. (January 2021, The Cryosphere)

   null (Ed.)

   Abstract. Ocean–sea-ice coupled models constrained by various observations provide different ice thickness estimates in the Antarctic. We evaluatecontemporary monthly ice thickness from four reanalyses in the Weddell Sea: the German contribution of the project Estimating the Circulation and Climate ofthe Ocean Version 2 (GECCO2), the Southern Ocean State Estimate (SOSE), the Ensemble Kalman Filter system based on the Nucleus for European Modelling of the Ocean (NEMO-EnKF) and the Global Ice–Ocean Modeling and Assimilation System (GIOMAS). The evaluation is performed againstreference satellite and in situ observations from ICESat-1, Envisat, upward-looking sonars and visual ship-based sea-ice observations. Compared withICESat-1, NEMO-EnKF has the highest correlation coefficient (CC) of 0.54 and lowest root mean square error (RMSE) of 0.44 m. Compared within situ observations, SOSE has the highest CC of 0.77 and lowest RMSE of 0.72 m. All reanalyses underestimate ice thickness near the coast ofthe western Weddell Sea with respect to ICESat-1 and in situ observations even though these observational estimates may be biased low. GECCO2 andNEMO-EnKF reproduce the seasonal variation in first-year ice thickness reasonably well in the eastern Weddell Sea. In contrast, GIOMAS ice thicknessperforms best in the central Weddell Sea, while SOSE ice thickness agrees most with the observations from the southern coast of the Weddell Sea. Inaddition, only NEMO-EnKF can reproduce the seasonal evolution of the large-scale spatial distribution of ice thickness, characterized by the thickice shifting from the southwestern and western Weddell Sea in summer to the western and northwestern Weddell Sea in spring. We infer that the thickice distribution is correlated with its better simulation of northward ice motion in the western Weddell Sea. These results demonstrate thepossibilities and limitations of using current sea-ice reanalysis for understanding the recent variability of sea-ice volume in the Antarctic. 

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2. Biophysical Drivers of Coastal Treeline Elevation

   https://doi.org/10.1029/2023JG007525  

   Molino, G D; Carr, J A; Ganju, N K; Kirwan, M L (December 2023, Journal of Geophysical Research: Biogeosciences)

   Abstract Sea level rise is leading to the rapid migration of marshes into coastal forests and other terrestrial ecosystems. Although complex biophysical interactions likely govern these ecosystem transitions, projections of sea level driven land conversion commonly rely on a simplified “threshold elevation” that represents the elevation of the marsh‐upland boundary based on tidal datums alone. To determine the influence of biophysical drivers on threshold elevations, and their implication for land conversion, we examined almost 100,000 high‐resolution marsh‐forest boundary elevation points, determined independently from tidal datums, alongside hydrologic, ecologic, and geomorphic data in the Chesapeake Bay, the largest estuary in the U.S. located along the mid‐Atlantic coast. We find five‐fold variations in threshold elevation across the entire estuary, driven not only by tidal range, but also salinity and slope. However, more than half of the variability is unexplained by these variables, which we attribute largely to uncaptured local factors including groundwater discharge, microtopography, and anthropogenic impacts. In the Chesapeake Bay, observed threshold elevations deviate from predicted elevations used to determine sea level driven land conversion by as much as the amount of projected regional sea level rise by 2050. These results suggest that local drivers strongly mediate coastal ecosystem transitions, and that predictions based on elevation and tidal datums alone may misrepresent future land conversion. 

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3. Retrieving the C and O Abundances of HR 7672 AB: A Solar-type Primary Star with a Benchmark Brown Dwarf

   https://doi.org/10.3847/1538-3881/ac56e2  

   Wang, Ji; Kolecki, Jared R.; Ruffio, Jean-Baptiste; Wang, Jason J.; Mawet, Dimitri; Baker, Ashley; Bartos, Randall; Blake, Geoffrey A.; Bond, Charlotte Z.; Calvin, Benjamin; et al (March 2022, The Astronomical Journal)

   Abstract A benchmark brown dwarf (BD) is a BD whose properties (e.g., mass and chemical composition) are precisely and independently measured. Benchmark BDs are valuable in testing theoretical evolutionary tracks, spectral synthesis, and atmospheric retrievals for substellar objects. Here, we report results of atmospheric retrieval on a synthetic spectrum and a benchmark BD, HR 7672 B, with petitRADTRANS . First, we test the retrieval framework on a synthetic PHOENIX BT-Settl spectrum with a solar composition. We show that the retrieved C and O abundances are consistent with solar values, but the retrieved C/O is overestimated by 0.13–0.18, which is about four times higher than the formal error bar. Second, we perform retrieval on HR 7672 B using high spectral-resolution data ( R = 35,000) from the Keck Planet Imager and Characterizer and near-infrared photometry. We retrieve [C/H], [O/H], and C/O to be −0.24 ± 0.05, −0.19 ± 0.04, and 0.52 ± 0.02. These values are consistent with those of HR 7672 A within 1.5 σ . As such, HR 7672 B is among only a few benchmark BDs (along with Gl 570 D and HD 3651 B) that have been demonstrated to have consistent elemental abundances with their primary stars. Our work provides a practical procedure of testing and performing atmospheric retrieval, and sheds light on potential systematics of future retrievals using high- and low-resolution data. 

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4. Farmland loss and retreat in the mid-Atlantic sea-level rise hotspot

   https://doi.org/10.6073/pasta/9d195aacee6a3a3ccbf3eef7cce95d0d  

   Chen, Yaping; Kirwan, Matthew L (January 2026, Environmental Data Initiative)

   {"Abstract":["Salinized farmlands consisting of dead crops and crop-free salt pans adjacent to salt marshes are a striking indicator of climate-driven sea-level rise. Here we quantify both the percent area change and vertical retreat rate of coastal farmlands between 1984 and 2022 along the US mid-Atlantic coast. The study region includes areas between 0-5 m above sea level with a special focus on the 0-2 m elevation - where saltwater intrusion is the most severe - across the Chesapeake Bay and the adjacent Delaware Bay. Particularly, the data package includes 2 shapefile datasets derived from four decades of Landsat satellite observations of coastal farmland dynamics. The two datasets are generated on the same spatial-scale and have the same spatial resolution of 0.075 km^2, both stored as hexagon grids with a side length of 170 m. Here we define "farmland retreat rate" (0-30 mm yr^-1) as the upward migration of the marsh-farmland boundary along coastal elevation averaged between 1984 and 2022, and the "farmland percent change" (0-100%) as the percent area change of arable farmland in each pixel from 1984 to 2022. All analyses are done on images after excluding man-made changes (e.g. farmland to forest conversion, farmland to urbanization)."]} 

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5. A novel retrieval of global dust optical depth and effective diameter based on MODIS thermal infrared observations

   https://doi.org/10.1016/j.rse.2025.115083  

   Zheng, Jianyu; Yu, Hongbin; Zhou, Yaping; Shi, Yingxi; Zhang, Zhibo; Di_Biagio, Claudia; Formenti, Paola; Smirnov, Alexander (October 2025, Remote Sensing of Environment)

   Airborne mineral dust significantly influences Earth’s climate through perturbing Earth’s radiation budget, modulating cloud formation and microphysical properties, and fertilizing the biosphere. Recent field campaigns have revealed substantially more coarse-mode dust particles in the atmosphere than previously recognized, yet current satellite retrievals and climate models inadequately represent these particles. This study presents a novel retrieval algorithm for dust aerosol optical depth at 10 μm (AOD10μm) and effective diameter (Deff) using Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared (TIR) observations over global land and ocean. Building upon the previous synergistic approach for MODIS and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), we improve the retrieval from CALIOP-track-limited coverage to full-swath MODIS observations at 10-km resolution over both ocean and land surfaces. The retrieval improvements include: (1) application of climatological CALIOP dust vertical profiles (2007–2017) to constrain dust vertical distribution for off-CALIOP-track pixels; (2) the improved optimization method to effectively handle nonmonotonic cost functions arising from temperature inversions within the Saharan Air Layer; and (3) extension to land surfaces through incorporation of MODIS-retrieved surface emissivity and ERA5 reanalysis data. Validation against coarse-mode AOD from global AERONET (N = 4703) and MAN (N = 1673) observations yields R = 0.82 and 0.85 for AOD10μm, with retrieval uncertainty characterized as ε = 15 % × AOD + 0.04. The retrieved Deff demonstrates excellent agreement with in-situ measurements collected from 24 field campaigns around the globe (R = 0.84, MBE = 0.23 μm, RMSE = 0.73 μm), capturing the particle size variation from near-source regions (Deff = 7–8 μm) to long-range transport (Deff = 3–5 μm). Case studies of dust events over the Namibian coast and trans-Atlantic corridor demonstrate the retrieval’s capability to resolve episodic dust properties and size-dependent deposition during transport. This improved retrieval addresses the critical observational gap for coarse and super-coarse dust particles (D > 5 μm), providing essential constraints for dust life cycle studies and climate model evaluation. 

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