Mapping Antarctic crevasses and their evolution with deep learning applied to satellite radar imagery The Cryosphere DOI 10.5194/tc-17-4421-2023 23 October 2023 The presence of crevasses in Antarctica influences how the ice sheet behaves. It is important, therefore, to collect data on the spatial distribution of crevasses and how they are changing. We present a method of mapping crevasses from satellite radar imagery and apply it to 7.5 years of images, covering Antarctica’s floating and grounded ice. We develop a method of measuring change in the density of crevasses and quantify increased fracturing in important parts of the West Antarctic Ice Sheet. Read more
ESD Ideas: Translating historical extreme weather events into a warmer world Earth System Dynamics DOI 10.5194/esd-14-1081-2023 20 October 2023 Adapting to climate change requires an understanding of how extreme weather events are changing. We propose a new approach to examine how the consequences of a particular weather pattern have been made worse by climate change, using an example of a severe windstorm that occurred in 1903. When this storm is translated into a warmer world, it produces higher wind speeds and increased rainfall, suggesting that this storm would be more damaging if it occurred today rather than 120 years ago. Read more
Global observations of aerosol indirect effects from marine liquid clouds Atmospheric Chemistry and Physics DOI 10.5194/acp-23-13125-2023 18 October 2023 Interactions between aerosol pollution and liquid clouds are one of the largest sources of uncertainty in the effective radiative forcing of climate over the industrial era. We use global satellite observations to decompose the forcing into components from changes in cloud-droplet number concentration, cloud water content, and cloud amount. Our results reduce uncertainty in these forcing components and clarify their relative importance. Read more
Technical note: NASAaccess – a tool for access, reformatting, and visualization of remotely sensed earth observation and climate data Hydrology and Earth System Sciences DOI 10.5194/hess-27-3621-2023 16 October 2023 We present an open-source platform in response to the NASA Open-Source Science Initiative for accessing and presenting quantitative remote-sensing earth observation,and climate data. With our platform scientists, stakeholders and concerned citizens can engage in the exploration, modelling, and understanding of data. We envisioned this platform as lowering the technical barriers and simplifying the process of accessing and leveraging additional modelling frameworks for data. Read more
The dehydration carousel of stratospheric water vapor in the Asian summer monsoon anticyclone Atmospheric Chemistry and Physics DOI 10.5194/acp-23-12935-2023 13 October 2023 We studied water vapour in a critical region of the atmosphere, the Asian summer monsoon anticyclone, using rare in situ observations. Our study shows that extremely high water vapour values observed in the stratosphere within the Asian monsoon anticyclone still undergo significant freeze-drying and that water vapour concentrations set by the Lagrangian dry point are a better proxy for the stratospheric water vapour budget than rare observations of enhanced water mixing ratios. Read more
Late Cenozoic sea-surface-temperature evolution of the South Atlantic Ocean Climate of the Past DOI 10.5194/cp-19-1931-2023 11 October 2023 We present two new sea surface temperature (SST) records in comparison with available SST records to reconstruct South Atlantic paleoceanographic evolution. Our results show a low SST gradient in the Eocene–early Oligocene due to the persistent gyral circulation. A higher SST gradient in the Middle–Late Miocene infers a stronger circumpolar current. The southern South Atlantic was the coldest region in the Southern Ocean and likely the main deep-water formation location in the Middle Miocene. Read more
Soil-biodegradable plastic films do not decompose in a lake sediment over 9 months of incubation Biogeosciences DOI 10.5194/bg-20-4213-2023 9 October 2023 Agriculture relies heavily on plastic mulch films, which may be transported to aquatic environments. We investigated the breakdown of soil-biodegradable agricultural mulch films in lake sediments. After 40 weeks, films were intact, and no significant CO2 or CH4 was produced from the biodegradable mulch films. We conclude that the mulch films we used have a low biodegradability in lake sediments. The sediment lacks the microbes needed to break down the biodegradable plastics that were used here. Read more
Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter Atmospheric Measurement Techniques DOI 10.5194/amt-16-4529-2023 6 October 2023 Atmospheric dust particles may present a preferential alignment due to their shape on long range transport. Since dust is abundant and plays a key role to global climate, the elusive observation of orientation will be a game changer to existing measurement techniques and the representation of particles in climate models. We utilize a specifically designed instrument, SolPol, and target the Sun from the ground for large polarization values under dusty conditions, a clear sign of orientation. Read more
Biomineralization of amorphous Fe-, Mn- and Si-rich mineral phases by cyanobacteria under oxic and alkaline conditions Biogeosciences DOI 10.5194/bg-20-4183-2023 4 October 2023 Iron and manganese are poorly soluble in oxic and alkaline solutions but much more soluble under anoxic conditions. As a result, authigenic minerals rich in Fe and/or Mn have been viewed as diagnostic of anoxic conditions. However, here we reveal a new case of biomineralization by specific cyanobacteria, forming abundant Fe(III)- and Mn(IV)-rich amorphous phases under oxic conditions in an alkaline lake. This might be an overlooked biotic contribution to the scavenging of Fe from water columns. Read more
Rapid saturation of cloud water adjustments to shipping emissions Atmospheric Chemistry and Physics DOI 10.5194/acp-23-12545-2023 2 October 2023 Aerosol from burning fuel changes cloud properties, e.g., the number of droplets and the content of water. Here, we study how clouds respond to different amounts of shipping aerosol. Droplet numbers increase linearly with increasing aerosol over a broad range until they stop increasing, while the amount of liquid water always increases, independently of emission amount. These changes in cloud properties can make them reflect more or less sunlight, which is important for the earth’s climate. Read more
SI-traceable validation of a laser spectrometer for balloon-borne measurements of water vapor in the upper atmosphere Atmospheric Measurement Techniques DOI 10.5194/amt-16-4391-2023 29 September 2023 The abundance of water vapor (H2O) in the upper atmosphere has a significant impact on the rate of global warming. We developed a new lightweight spectrometer (ALBATROSS) for H2O measurements aboard meteorological balloons. Here, we assess the accuracy and precision of ALBATROSS using metrology-grade reference gases. The results demonstrate the exceptional potential of mid-infrared laser absorption spectroscopy as a new reference method for in situ measurements of H2O in the upper atmosphere. Read more
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