Emulating lateral gravity wave propagation in a global chemistry–climate model (EMAC v2.55.2) through horizontal flux redistribution Geoscientific Model Development DOI 10.5194/gmd-16-5561-2023 27 September 2023 The columnar approach of gravity wave (GW) schemes results in dynamical model biases, but parallel decomposition makes horizontal GW propagation computationally unfeasible. In the global model EMAC, we approximate it by GW redistribution at one altitude using tailor-made redistribution maps generated with a ray tracer. More spread-out GW drag helps reconcile the model with observations and close the 60°S GW gap. Polar vortex dynamics are improved, enhancing climate model credibility. Read more
Methane emissions due to reservoir flushing: a significant emission pathway? Biogeosciences DOI 10.5194/bg-20-4057-2023 25 September 2023 Based on a large dataset of seasonally resolved methane (CH4) pore water concentrations in a reservoir’s sediment, we assess the significance of CH4 emissions due to reservoir flushing. In the studied reservoir, CH4 emissions caused by one flushing operation can represent 7 %–14 % of the annual CH4 emissions and depend on the timing of the flushing operation. In reservoirs with high sediment loadings, regular flushing may substantially contribute to the overall CH4 emissions. Read more
Element ∕ Ca ratios in Nodosariida (Foraminifera) and their potential application for paleoenvironmental reconstructions Biogeosciences DOI 10.5194/bg-20-4043-2023 22 September 2023 We analyzed Mg / Ca and other El / Ca (Na / Ca, B / Ca, Sr / Ca and Ba / Ca) in Nodosariata. Their calcite chemistry is markedly different to that of the other calcifying orders of foraminifera. We show a relation between the species average Mg / Ca and its sensitivity to changes in temperature. Differences were reflected in both the Mg incorporation and the sensitivities of Mg / Ca to temperature. Read more
Advancing the estimation of future climate impacts within the United States Earth System Dynamics DOI 10.5194/esd-14-1015-2023 20 September 2023 This study utilizes a reduced-complexity model, Framework for Evaluating Damages and Impacts (FrEDI), to assess the impacts from climate change in the United States across 10 000 future probabilistic emission and socioeconomic projections. Climate-driven damages are largest for the health category, with the majority of damages in this category coming from the valuation estimates of premature mortality attributable to climate-driven changes in extreme temperature and air quality scenarios. Read more
Molecular simulations reveal that heterogeneous ice nucleation occurs at higher temperatures in water under capillary tension Atmospheric Chemistry and Physics DOI 10.5194/acp-23-10625-2023 18 September 2023 Using computer simulations of water, we find that water under tension freezes more easily than under normal conditions. A linear equation describes how freezing temperature increases with tension. Accordingly, simulations show that naturally occurring tension in water capillary bridges leads to higher freezing temperatures. This work is an early step in determining if atmospheric cloud droplets freeze due to naturally occurring tension, for example, during processes such as droplet collisions. Read more
Modes of Antarctic tidal grounding line migration revealed by Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) laser altimetry The Cryosphere DOI 10.5194/tc-17-4079-2023 15 September 2023 We develop a method using ICESat-2 data to measure how Antarctic grounding lines (GLs) migrate across the tide cycle. At an ice plain on the Ronne Ice Shelf we observe 15 km of tidal GL migration, the largest reported distance in Antarctica, dominating any signal of long-term migration. We identify four distinct migration modes, which provide both observational support for models of tidal ice flexure and GL migration and insights into ice shelf–ocean–subglacial interactions in grounding zones. Read more
High-resolution data reveal a surge of biomass loss from temperate and Atlantic pine forests, contextualizing the 2022 fire season distinctiveness in France Biogeosciences DOI 10.5194/bg-20-3803-2023 13 September 2023 This study analyses the ecological impact of the 2022 summer fire season in France by using high-resolution satellite data. The total biomass loss was 2.553 Mt, equivalent to a 17 % increase of the average natural mortality of all French forests. While Mediterranean forests had a lower biomass loss, there was a drastic increase in burned area and biomass loss over the Atlantic pine forests and temperate forests. This result revisits the distinctiveness of the 2022 fire season. Read more
Atmospheric drivers of melt-related ice speed-up events on the Russell Glacier in southwest Greenland The Cryosphere DOI 10.5194/tc-17-3933-2023 11 September 2023 The Greenland Ice Sheet contributes strongly to sea level rise in the warming climate. One process that can affect the ice sheet’s mass balance is short-term ice speed-up events. These can be caused by high melting or rainfall as the water flows underneath the glacier and allows for faster sliding. In this study we found three main weather patterns that cause such ice speed-up events on the Russell Glacier in southwest Greenland and analysed how they induce local melting and ice accelerations. Read more
Analysis of in situ measurements of electron, ion and neutral temperatures in the lower thermosphere–ionosphere Annales Geophysicae DOI 10.5194/angeo-41-339-2023 8 September 2023 The relation between electron, ion and neutral temperatures in the lower thermosphere–ionosphere (LTI) is key to understanding the energy balance and transfer between species. However, their simultaneous measurement is rare in the LTI. Based on data from the AE-C, AE-D, AE-E and DE-2 satellites of the 1970s and 1980s, a large number of events where neutrals are hotter than ions are identified and statistically analysed. Potential mechanisms that could trigger these events are proposed. Read more
Calibration of groundwater seepage against the spatial distribution of the stream network to assess catchment-scale hydraulic properties Hydrology and Earth System Sciences DOI 10.5194/hess-27-3221-2023 6 September 2023 We propose a model calibration method constraining groundwater seepage in the hydrographic network. The method assesses the hydraulic properties of aquifers in regions where perennial streams are directly fed by groundwater. The estimated hydraulic conductivity appear to be highly sensitive to the spatial extent and density of streams. Such an approach improving subsurface characterization from surface information is particularly interesting for ungauged basins. Read more
