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. OLYMPEX campaign data">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. WAVEWATCH III (v6.07) wave action source terms to GPU">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
