The three-dimensional structure of fronts in mid-latitude weather systems in numerical weather prediction models Geoscientific Model Development DOI 10.5194/gmd-16-4427-2023 7 August 2023 We investigate the benefit of objective 3-D front detection with modern interactive visual analysis techniques for case studies of extra-tropical cyclones and comparisons of frontal structures between different numerical weather prediction models. The 3-D frontal structures show agreement with 2-D fronts from surface analysis charts and augment them in the vertical dimension. We see great potential for more complex studies of atmospheric dynamics and for operational weather forecasting. Read more
DSCIM-Coastal v1.1: an open-source modeling platform for global impacts of sea level rise Geoscientific Model Development DOI 10.5194/gmd-16-4331-2023 4 August 2023 This work presents a novel open-source modelling platform for evaluating future sea level rise (SLR) impacts. Using nearly 10 000 discrete coastline segments around the world, we estimate 21st-century costs for 230 SLR and socioeconomic scenarios. We find that annual end-of-century costs range from USD 100 billion under a 2 °C warming scenario with proactive adaptation to 7 trillion under a 4 °C warming scenario with minimal adaptation, illustrating the cost-effectiveness of coastal adaptation. Read more
Detection of large-scale cloud microphysical changes within a major shipping corridor after implementation of the International Maritime Organization 2020 fuel sulfur regulations Atmospheric Chemistry and Physics DOI 10.5194/acp-23-8259-2023 2 August 2023 Fuel sulfur regulations were implemented for ships in 2020 to improve air quality but may also accelerate global warming. We use spatial statistics and satellite retrievals to detect changes in the size of cloud droplets and find evidence for a resulting decrease in cloud brightness within a major shipping corridor after the sulfur limits went into effect. Our results confirm both that the regulations are being followed and that they are having a warming influence via their effect on clouds. Read more
Design and performance of the Hotrod melt-tip ice-drilling system Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-12-121-2023 31 July 2023 We describe a new drill for glaciers and ice sheets. Instead of drilling down into the ice, via mechanical action, our drill melts into the ice. Our goal is simply to pull a cable of temperature sensors on a one-way trip down to the ice–bed interface. Here, we describe the design and testing of our drill. Under laboratory conditions, our melt-tip drill has an efficiency of ~35 % with a theoretical maximum penetration rate of ~12 m h^-1. Under field conditions, our efficiency is just ~15 %. Read more
Continuous weekly monitoring of methane emissions from the Permian Basin by inversion of TROPOMI satellite observations Atmospheric Chemistry and Physics DOI 10.5194/acp-23-7503-2023 28 July 2023 We use TROPOMI satellite observations to quantify weekly methane emissions from the US Permian oil and gas basin from May 2018 to October 2020. We find that Permian emissions are highly variable, with diverse economic and activity drivers. The most important drivers during our study period were new well development and natural gas price. Permian methane intensity averaged 4.6% and decreased by 1% per year. Read more
Brief communication: How deep is the snow on Mount Everest? The Cryosphere DOI 10.5194/tc-17-2625-2023 26 July 2023 There is very strong scientific and public interest regarding the snow thickness on Mountain Everest. Previously reported snow depths derived by different methods and instruments ranged from 0.92 to 3.5 m. Our measurements in 2022 provide the first clear radar image of the snowpack at the top of Mount Everest. The snow thickness at Earth’s summit was averaged to be 9.5 ± 1.2 m. This updated snow thickness is considerably deeper than values reported during the past 5 decades. Read more
All about nitrite: exploring nitrite sources and sinks in the eastern tropical North Pacific oxygen minimum zone Biogeosciences DOI 10.5194/bg-20-2499-2023 24 July 2023 Nitrogen (N) is essential for life; thus, its availability plays a key role in determining marine productivity. Using incubations of seawater spiked with a rare form of N measurable on a mass spectrometer, we quantified microbial pathways that determine marine N availability. The results show that pathways that recycle N have higher rates than those that result in its loss from biomass and present new evidence for anaerobic nitrite oxidation, a process long thought to be strictly aerobic. Read more
Review article: Large fluctuations in non-equilibrium physics Nonlinear Processes in Geophysics DOI 10.5194/npg-30-253-2023 21 July 2023 Non-equilibrium is dominant in geophysical and climate phenomena. Most of the processes that characterize energy flow occur far from equilibrium. These range from very large systems, such as weather patterns or ocean currents that remain far from equilibrium, owing to an influx of energy, to biological structures. In the last decades, progress in non-equilibrium physics has come from the study of very rare fluctuations, and this paper provides an introduction to these theoretical developments. Read more
Dense water formation in the eastern Mediterranean under a global warming scenario Ocean Science DOI 10.5194/os-19-941-2023 19 July 2023 Global warming may strongly affect dense water formation in the eastern Mediterranean, potentially impacting basin circulation and water properties. We find that at the end of the century dense water formation is reduced by 75 % for the Adriatic, 84 % for the Aegean, and 83 % for the Levantine Sea. This reduction is caused by changes in the temperature and salinity of surface and intermediate waters, which strengthen the vertical stratification, hampering deep convection. Read more
Brief communication: Rapid ∼ 335 × 106 m3 bed erosion after detachment of the Sedongpu Glacier (Tibet) The Cryosphere DOI 10.5194/tc-17-2533-2023 17 July 2023 Following the detachment of the 130 × 10^6 m^3 Sedongpu Glacier (south-eastern Tibet) in 2018, the Sedongpu Valley underwent massive large-volume landscape changes. An enormous volume of in total around 330 × 10^6 m^3 was rapidly eroded, forming a new canyon of up to 300 m depth, 1 km width, and almost 4 km length. Such consequences of glacier change in mountains have so far not been considered at this magnitude and speed. Read more
Impact of deoxygenation and warming on global marine species in the 21st century Biogeosciences DOI 10.5194/bg-20-2425-2023 14 July 2023 Ocean temperature and oxygen shape marine habitats together with species’ characteristics. We calculated the impacts of projected 21st-century warming and oxygen loss on the contemporary habitat volume of 47 marine species and described the drivers of these impacts. Most species lose less than 5 % of their habitat at 2 ◦C of global warming, but some species incur losses 2–3 times greater than that. We also calculate which species may be most vulnerable to climate change and why this is the case. Read more
Impact of a strong volcanic eruption on the summer middle atmosphere in UA-ICON simulations Atmospheric Chemistry and Physics DOI 10.5194/acp-23-7001-2023 12 July 2023 Strong volcanic eruptions are able to alter the temperature and the circulation of the middle atmosphere. This study simulates the atmospheric response to an idealized strong tropical eruption and focuses on the impact on the mesosphere. The simulations show a warming of the polar summer mesopause in the first November after the eruption. Our study indicates that this is mainly due to dynamical coupling in the summer hemisphere with a potential contribution from interhemispheric coupling. Read more
Quantifying land carbon cycle feedbacks under negative CO2 emissions Biogeosciences DOI 10.5194/bg-20-2283-2023 10 July 2023 We propose a new method to quantify carbon cycle feedbacks under negative CO2 emissions. Our method isolates the lagged carbon cycle response to preceding positive emissions from the response to negative emissions. Our findings suggest that feedback parameters calculated with the novel approach are larger than those calculated with the conventional approach whereby carbon cycle inertia is not corrected for, with implications for the effectiveness of carbon dioxide removal in reducing CO2 levels. Read more
Particle shapes and infrared extinction spectra of nitric acid dihydrate (NAD) crystals: optical constants of the β-NAD modification Atmospheric Chemistry and Physics DOI 10.5194/acp-23-6789-2023 7 July 2023 Polar stratospheric clouds (PSCs) play an important role in the depletion of stratospheric ozone. They can consist of different chemical species, including crystalline nitric acid hydrates. We found that mineral dust or meteoric ablation material can efficiently catalyse the formation of a specific phase of nitric acid dihydrate crystals. We determined predominant particle shapes and infrared optical properties of these crystals, which are important inputs for remote sensing detection of PSCs. Read more
Diurnal carbon monoxide observed from a geostationary infrared hyperspectral sounder: first result from GIIRS on board FengYun-4B Atmospheric Measurement Techniques DOI 10.5194/amt-16-3059-2023 5 July 2023 Observations from geostationary orbit provide contiguous coverage with a high temporal resolution, representing an important advancement over current low-Earth-orbit instruments. Using measurements from GIIRS on board China’s FengYun satellite, the world’s first geostationary hyperspectral infrared sounder, we showed the first results of diurnal CO in eastern Asia from a geostationary orbit, which will have great potential in improving local and global air quality and climate research. Read more
Opinion: How fear of nuclear winter has helped save the world, so far Atmospheric Chemistry and Physics DOI 10.5194/acp-23-6691-2023 3 July 2023 A nuclear war could produce a nuclear winter, with catastrophic consequences for global food supplies. Nuclear winter theory helped to end the nuclear arms race in the 1980s, but more than 10,000 nuclear weapons still exist. This means they can be used, by unstable leaders, accidentally from technical malfunctions or human error, or by terrorists. Therefore, it is urgent for scientists to study these issues, broadly communicate their results, and work for the elimination of nuclear weapons. Read more
Hyperspectral imaging sediment core scanning tracks high-resolution Holocene variations in (an)oxygenic phototrophic communities at Lake Cadagno, Swiss Alps Biogeosciences DOI 10.5194/bg-20-2221-2023 30 June 2023 This study shows, for the first time, that hyperspectral imaging can detect bacteriochlorophyll pigments produced by green sulfur bacteria in sediment cores. We tested our method on cores from Lake Cadagno, Switzerland, and were able to reconstruct high-resolution variations in the abundance of green and purple sulfur bacteria over the past 12 700 years. Climate conditions, flood events, and land use had major impacts on the lake’s biogeochemical conditions over short and long timescales. Read more
Rate-induced tipping in natural and human systems Earth System Dynamics DOI 10.5194/esd-14-669-2023 28 June 2023 Complex systems can undergo abrupt changes or tipping points when external forcing crosses a critical level and are of increasing concern because of their severe impacts. However, tipping points can also occur when the external forcing changes too quickly without crossing any critical levels, which is very relevant for Earth’s systems and contemporary climate. We give an intuitive explanation of such rate-induced tipping and provide illustrative examples from natural and human systems. Read more
Contribution of solitons to enhanced rogue wave occurrence in shallow depths: a case study in the southern North Sea Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-2053-2023 26 June 2023 Rogue waves exceed twice the significant wave height. They occur more often than expected in the shallow waters off Norderney. When applying a nonlinear Fourier transform for the Korteweg–de Vries equation to wave data from Norderney, we found differences in the soliton spectra of time series with and without rogue waves. A strongly outstanding soliton in the spectrum indicated an enhanced probability for rogue waves. We could attribute spectral solitons to the measured rogue waves. Read more
Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective Ocean Science DOI 10.5194/os-19-769-2023 23 June 2023 This study uses the trajectories of water parcels traced within an ocean model simulation to identify the pathways responsible for the seasonal cycle of dense water formation (overturning) in the eastern subpolar North Atlantic. We show that overturning seasonality is due to the fastest water parcels circulating within the eastern basins in less than 8.5 months. Slower pathways set the average strength of overturning in this region since water parcels cannot escape intense wintertime cooling. Read more
Applying machine learning to improve the near-real-time products of the Aura Microwave Limb Sounder Atmospheric Measurement Techniques DOI 10.5194/amt-16-2733-2023 21 June 2023 The algorithm that produces the near-real-time data products of the Aura Microwave Limb Sounder has been updated. The new algorithm is based on machine learning techniques and yields data products with much improved accuracy. It is shown that the new algorithm outperforms the previous versions, even when it is trained on only a few years of satellite observations. This confirms the potential of applying machine learning to the near-real-time efforts of other current and future mission concepts. Read more
The 2018 west-central European drought projected in a warmer climate: how much drier can it get? Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1921-2023 19 June 2023 To examine the impact of global warming on west-central European droughts, we have constructed future analogues of recent summers. Extreme droughts like 2018 further intensify, and the local temperature rise is much larger than in most summers. Years that went hardly noticed in the present-day climate may emerge as very dry and hot in a warmer world. The changes can be directly linked to real-world events, which makes the results very tangible and hence useful for climate change communication. Read more
The Volyn biota (Ukraine) – indications of 1.5 Gyr old eukaryotes in 3D preservation, a spotlight on the “boring billion” Biogeosciences DOI 10.5194/bg-20-1901-2023 16 June 2023 This research describes the occurrence of Precambrian fossils, with exceptionally well preserved morphology in 3D. These microfossils reach a size of millimeters (possibly up to centimeters) and thus indicate the presence of multicellular eukaryotes. Many of them are filamentous, but other types were also found. These fossils lived in a depth of several hundred meters and thus provide good evidence of a continental the deep biosphere, from a time generally considered as the “boring billion”. Read more
Pace v0.2: a Python-based performance-portable atmospheric model Geoscientific Model Development DOI 10.5194/gmd-16-2719-2023 14 June 2023 It is hard for scientists to write code which is efficient on different kinds of supercomputers. Python is popular for its user-friendliness. We converted a Fortran code, simulating Earth’s atmosphere, into Python. This new code auto-converts to a faster language for processors or graphic cards. Our code runs 3.5–4 times faster on graphic cards than the original on processors in a specific supercomputer system. Read more
What distinguishes 100-year precipitation extremes over central European river catchments from more moderate extreme events? Weather and Climate Dynamics DOI 10.5194/wcd-4-427-2023 12 June 2023 In this study, we analyse the generic atmospheric processes of very extreme, 100-year precipitation events in large central European river catchments and the corresponding differences to less extreme events, based on a large time series (~1200 years) of simulated but realistic daily precipitation events from the ECMWF. Depending on the catchment, either dynamical mechanisms or thermodynamic conditions or a combination of both distinguish 100-year events from less extreme precipitation events. Read more
Response of the sea surface temperature to heatwaves during the France 2022 meteorological summer Ocean Science DOI 10.5194/os-19-629-2023 9 June 2023 In the summer of 2022, France experienced a series of unprecedented heatwaves. This study is the first to examine the response of sea surface temperatures to these events, using spatial operational data and attributing the observed abnormally warm SSTs to atmospheric forcings. The findings of this study underscore the critical need for an efficient and sustainable operational system to monitor alterations that threaten the oceans in the context of climate change. Read more
Paleontology-themed comics and graphic novels, their potential for scientific outreach, and the bilingual graphic novel EUROPASAURUS – Life on Jurassic Islands Geoscience Communication DOI 10.5194/gc-6-45-2023 5 June 2023 We give an overview of influential comics and graphic novels on paleontological themes, especially dinosaurs. We explain their different forms of representation and narration, and how they were influenced by the contemporary state of knowledge. The second part deals with the creation of the bilingual graphic novel EUROPASAURUS – Life on Jurassic Islands, a textless comic book, and how this book was perceived by the public. Read more
Constraints on long-term cliff retreat and intertidal weathering at weak rock coasts using cosmogenic 10Be, nearshore topography and numerical modelling Earth Surface Dynamics DOI 10.5194/esurf-11-429-2023 2 June 2023 This study uses a coastal evolution model to interpret cosmogenic beryllium-10 concentrations and topographic data and, in turn, quantify long-term cliff retreat rates for four chalk sites on the south coast of England. By using a process-based model, clear distinctions between intertidal weathering rates have been recognised between chalk and sandstone rock coast sites, advocating the use of process-based models to interpret the long-term behaviour of rock coasts. Read more
The extremely hot and dry 2018 summer in central and northern Europe from a multi-faceted weather and climate perspective Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1699-2023 31 May 2023 The objective of this study was to perform a comprehensive, multi-faceted analysis of the 2018 extreme summer in terms of heat and drought in central and northern Europe, with a particular focus on Germany. A combination of favourable large-scale conditions and locally dry soils were related with the intensity and persistence of the events. We also showed that such extremes have become more likely due to anthropogenic climate change and might occur almost every year under +2 °C of global warming. Read more
Quantifying gender gaps in seismology authorship Solid Earth DOI 10.5194/se-14-485-2023 29 May 2023 We investigate women’s representation in seismology to raise awareness of existing gender disparities. By analysing the authorship of peer-reviewed articles, we identify lower representation of women among single authors, high-impact authors, and highly productive authors. Seismology continues to be a male-dominated field, and trends suggest that parity is decades away. These gaps are an obstacle to women’s career advancement and, if neglected, may perpetuate the leaky-pipeline problem. Read more
Opinion: The scientific and community-building roles of the Geoengineering Model Intercomparison Project (GeoMIP) – past, present, and future Atmospheric Chemistry and Physics DOI 10.5194/acp-23-5149-2023 26 May 2023 Geoengineering indicates methods aiming to reduce the temperature of the planet by means of reflecting back a part of the incoming radiation before it reaches the surface or allowing more of the planetary radiation to escape into space. It aims to produce modelling experiments that are easy to reproduce and compare with different climate models, in order to understand the potential impacts of these techniques. Here we assess its past successes and failures and talk about its future. Read more
Evaluation of liquefaction triggering potential in Italy: a seismic-hazard-based approach Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1685-2023 24 May 2023 In the present study, we analyse ground-motion hazard maps and hazard disaggregation in order to define areas in Italy where liquefaction triggering due to seismic activity can not be excluded. The final result is a screening map for all of Italy that classifies sites in terms of liquefaction triggering potential according to their seismic hazard level. The map and the associated data are freely accessible at the following web address: www.distav.unige.it/rsni/milq.php. Read more
Reversible ice sheet thinning in the Amundsen Sea Embayment during the Late Holocene The Cryosphere DOI 10.5194/tc-17-1787-2023 22 May 2023 Samples of bedrock recovered from below the West Antarctic Ice Sheet show that part of the ice sheet was thinner several thousand years ago than it is now and subsequently thickened. This is important because of concern that present ice thinning in this region may lead to rapid, irreversible sea level rise. The past episode of thinning at this site that took place in a similar, although not identical, climate was not irreversible; however, reversal required at least 3000 years to complete. Read more
Reconstructing ocean carbon storage with CMIP6 Earth system models and synthetic Argo observations Biogeosciences DOI 10.5194/bg-20-1671-2023 19 May 2023 We present a new method for reconstructing ocean carbon using climate models and temperature and salinity observations. To test this method, we reconstruct modelled carbon using synthetic observations consistent with current sampling programmes. Sensitivity tests show skill in reconstructing carbon trends and variability within the upper 2000 m. Our results indicate that this method can be used for a new global estimate for ocean carbon content. Read more
Methane emissions are predominantly responsible for record-breaking atmospheric methane growth rates in 2020 and 2021 Atmospheric Chemistry and Physics DOI 10.5194/acp-23-4863-2023 17 May 2023 Our understanding of recent changes in atmospheric methane has defied explanation. Since 2007, the atmospheric growth of methane has accelerated to record-breaking values in 2020 and 2021. We use satellite observations of methane to show that (1) increasing emissions over the tropics are mostly responsible for these recent atmospheric changes, and (2) changes in the OH sink during the 2020 Covid-19 lockdown can explain up to 34% of changes in atmospheric methane for that year. Read more
Rescuing historical weather observations improves quantification of severe windstorm risks Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1465-2023 15 May 2023 We examine a severe windstorm that occurred in February 1903 and caused significant damage in the UK and Ireland. Using newly digitized weather observations from the time of the storm, combined with a modern weather forecast model, allows us to determine why this storm caused so much damage. We demonstrate that the event is one of the most severe windstorms to affect this region since detailed records began. The approach establishes a new tool to improve assessments of risk from extreme weather. Read more
Causal deep learning models for studying the Earth system Geoscientific Model Development DOI 10.5194/gmd-16-2149-2023 12 May 2023 A recent statistical approach for studying relations in the Earth system is to train deep learning (DL) models to predict Earth system variables given one or several others and use interpretable DL to analyse the relations learned by the models. Here, we propose to combine the approach with a theorem from causality research to ensure that the deep learning model learns causal rather than spurious relations. As an example, we apply the method to study soil-moisture–precipitation coupling. Read more
Evaluation of polarimetric ice microphysical retrievals with OLYMPEX campaign data Atmospheric Measurement Techniques DOI 10.5194/amt-16-2089-2023 10 May 2023 We present an evaluation of current retrieval techniques in the ice phase applied to polarimetric radar measurements with collocated in situ observations of aircraft conducted over the Olympic Mountains, Washington State, during winter 2015. Radar estimates of ice properties agreed most with aircraft observations in regions with pronounced radar signatures, but uncertainties were identified that indicate issues of some retrievals, particularly in warmer temperature regimes. Read more
Brief communication: The northwest Himalaya towns slipping towards potential disaster Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1425-2023 8 May 2023 The NW Himalaya has been one of the most affected terrains of the Himalaya, subject to disastrous landslides. This article focuses on two towns (Joshimath and Bhatwari) of the NW Himalaya, which have been witnessing subsidence for decades. We used a slope stability simulation to determine the response of the hill slopes accommodating these towns under various loading conditions. We found that the maximum displacement in these hill slopes might reach up to 20–25 m. Read more
Prediction of the absolute hydraulic conductivity function from soil water retention data Hydrology and Earth System Sciences DOI 10.5194/hess-27-1565-2023 5 May 2023 The soil hydraulic conductivity function is usually predicted from the water retention curve (WRC) with the requirement of at least one measured conductivity data point for scaling the function. We propose a new scheme of absolute hydraulic conductivity prediction from the WRC without the need of measured conductivity data. Testing the new prediction with independent data shows good results. This scheme can be used when insufficient or no conductivity data are available. Read more
Porting the WAVEWATCH III (v6.07) wave action source terms to GPU Geoscientific Model Development DOI 10.5194/gmd-16-1445-2023 3 May 2023 Wind-generated waves play an important role in modifying physical processes at the air–sea interface, but they have been traditionally excluded from climate models due to the high computational cost of running spectral wave models for climate simulations. To address this, our work identified and accelerated the computationally intensive section of WAVEWATCH III on GPU using OpenACC. This allows for high-resolution modelling of atmosphere–wave–ocean feedbacks in century-scale climate integrations. Read more
Selective deuteration as a tool for resolving autoxidation mechanisms in α-pinene ozonolysis Atmospheric Chemistry and Physics DOI 10.5194/acp-23-4373-2023 1 May 2023 We discuss and show the viability of a method where multiple isotopically labelled precursors are used for probing the formation pathways of highly oxygenated organic molecules (HOMs) from the oxidation of the monoterpene a-pinene. HOMs are very important for secondary organic aerosol (SOA) formation in forested regions, and monoterpenes are the single largest source of SOA globally. The fast reactions forming HOMs have thus far remained elusive despite considerable efforts over the last decade. Read more
Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean Biogeosciences DOI 10.5194/bg-20-1423-2023 28 April 2023 Arctic warming accelerates permafrost thaw and release of terrestrial organic matter (OM) via rivers to the Arctic Ocean. We compared particulate organic carbon (POC), total suspended matter, and C isotopes (δ13C and Δ14C of POC) in the Lena delta and Lena River along a ∼1600 km transect. We show that the Lena delta, as an interface between the Lena River and the Arctic Ocean, plays a crucial role in determining the qualitative and quantitative composition of OM discharged into the Arctic Ocean. Read more
Patterns and drivers of water quality changes associated with dams in the Tropical Andes Hydrology and Earth System Sciences DOI 10.5194/hess-27-1493-2023 26 April 2023 Dams are an important and rapidly growing means of energy generation in the Tropical Andes of South America. To assess the impacts of dams in the region, we assessed differences in the upstream and downstream water quality of all hydropower dams in Colombia. We found evidence of substantial dam-induced changes in water temperature, dissolved oxygen concentration and suspended sediments. Dam-induced changes in Colombian waters violate regulations and are likely impacting aquatic life. Read more
Foreign emissions exacerbate PM2.5 pollution in China through nitrate chemistry Atmospheric Chemistry and Physics DOI 10.5194/acp-23-4149-2023 24 April 2023 Research on the sources of Chinese PM2.5 pollution has focused on the contributions of China’s domestic emissions. However, the impact of foreign anthropogenic emissions has typically been simplified or neglected. Here we find that foreign anthropogenic emissions play an important role in Chinese PM2.5 pollution through chemical interactions between foreign-transported pollutants and China’s local emissions. Thus, foreign emission reductions are essential for improving Chinese air quality. Read more
Uncertainty in aerosol–cloud radiative forcing is driven by clean conditions Atmospheric Chemistry and Physics DOI 10.5194/acp-23-4115-2023 21 April 2023 The impact of aerosols on clouds is one of the largest uncertainties in the human forcing of the climate. Aerosol can increase the concentrations of droplets in clouds, but observational and model studies produce widely varying estimates of this effect. We show that these estimates can be reconciled if only polluted clouds are studied, but this is insufficient to constrain the climate impact of aerosol. The uncertainty in aerosol impact on clouds is currently driven by cases with little aerosol. Read more
A multi-disciplinary analysis of the exceptional flood event of July 2021 in central Europe – Part 2: Historical context and relation to climate change Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1287-2023 19 April 2023 Heavy precipitation in July 2021 led to widespread floods in western Germany and neighbouring countries. The event was among the five heaviest precipitation events of the past 70 years in Germany, and the river discharges exceeded by far the statistical 100-year return values. Simulations of the event under future climate conditions revealed a strong and non-linear effect on flood peaks: for +2K global warming, an 18% increase in rainfall led to a 39% increase of the flood peak in the Ahr river. Read more
Brief communication: On the extremeness of the July 2021 precipitation event in western Germany Natural Hazards and Earth System Sciences DOI 10.5194/nhess-23-1227-2023 17 April 2023 Estimating the severity of a rainfall event based on the damage caused is easy but highly depends on the affected region. A less biased measure for the extremeness of an event is its rarity combined with its spatial extent. In this brief communication, we investigate the sensitivity of such measures to the underlying dataset and highlight the importance of considering multiple spatial and temporal scales using the devastating rainfall event in July 2021 in central Europe as an example. Read more
Investigation of links between dynamical scenarios and particularly high impact of Aeolus on numerical weather prediction (NWP) forecasts Author(s): Anne Martin, Martin Weissmann, and Alexander Cress Weather and Climate Dynamics DOI 10.5194/wcd-4-249-2023 14 April 2023 Global wind profiles from the Aeolus satellite mission are an important recent substitute for the Global Observing System, showing an overall positive impact on numerical weather prediction forecasts. This study highlights atmospheric dynamic phenomena constituting pathways for significant improvement of Aeolus for future studies, including large-scale tropical circulation systems and the interaction of tropical cyclones undergoing an extratropical transition with the midlatitude waveguide. Read more
The new Kr-86 excess ice core proxy for synoptic activity: West Antarctic storminess possibly linked to Intertropical Convergence Zone (ITCZ) movement through the last deglaciation Climate of the Past DOI 10.5194/cp-19-579-2023 12 April 2023 It is unclear how different components of the global atmospheric circulation, such as the El Niño effect, respond to large-scale climate change. We present a new ice core gas proxy, called krypton-86 excess, that reflects past storminess in Antarctica. We present data from 11 ice cores that suggest the new proxy works. We present a reconstruction of changes in West Antarctic storminess over the last 24000 years and suggest these are caused by north–south movement of the tropical rain belt. Read more