Heterogeneity and chemical reactivity of the remote troposphere defined by aircraft measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-21-13729-2021 3 November 2021 The NASA Atmospheric Tomography (ATom) mission built a climatology of the chemical composition of tropospheric air parcels throughout the middle of the Pacific and Atlantic oceans. The level of detail allows us to reconstruct the photochemical budgets of O3 and CH4 over these vast, remote regions. We find that most of the chemical heterogeneity is captured at the resolution used in current global chemistry models and that the majority of reactivity occurs in the “hottest” 20 % of parcels. Read more
Deformation-enhanced diagenesis and bacterial proliferation in the Nankai accretionary prism Solid Earth DOI 10.5194/se-12-2067-2021 1 November 2021 Sediments accumulated in accretionary prisms are deformed by the compression imposed by plate subduction. Here we show that deformation of the sediments transforms some minerals in them. We suggest that these mineral transformations are due to the proliferation of microorganisms boosted by deformation. Deformation-enhanced microbial proliferation may change our view of sedimentary and tectonic processes in subduction zones. Read more
Geochemical consequences of oxygen diffusion from the oceanic crust into overlying sediments and its significance for biogeochemical cycles based on sediments of the northeast Pacific Biogeosciences DOI 10.5194/bg-18-4965-2021 29 October 2021 Oxygen penetrates sediments not only from the ocean bottom waters but also from the basement. The impact of the latter is poorly understood. We show that this basement oxygen has a clear impact on the nitrogen cycle, the redox state, and the distribution of manganese, nickel cobalt and organic matter in the sediments. This is important for (1) global biogeochemical cycles, (2) understanding sedimentary life and (3) the interpretation of the sediment record to reconstruct the past. Read more
Wildfire smoke, Arctic haze, and aerosol effects on mixed-phase and cirrus clouds over the North Pole region during MOSAiC: an introduction Atmospheric Chemistry and Physics DOI 10.5194/acp-21-13397-2021 27 October 2021 A Raman lidar was operated aboard the icebreaker Polarstern during MOSAiC and monitored aerosol and cloud layers in the central Arctic up to 30 km height. The article provides an overview of the spectrum of aerosol profiling observations and shows aerosol–cloud interaction studies for liquid-water and ice clouds. A highlight was the detection of a 10 km deep wildfire smoke layer over the North Pole up to 17 km height from the fire season of 2019, which persisted over the whole winter period. Read more
Rheological stratification in impure rock salt during long-term creep: morphology, microstructure, and numerical models of multilayer folds in the Ocnele Mari salt mine, Romania Solid Earth DOI 10.5194/se-12-2041-2021 25 October 2021 We analyse folded multilayer sequences in the Ocnele Mari salt mine (Romania) to gain insight into the long-term rheological behaviour of rock salt. Our results indicate the large role of even a small number of impurities in the rock salt for its effective mechanical behaviour. We demonstrate how the development of folds that occur at various scales can be used to constrain the viscosity ratio in the deformed multilayer sequence. Read more
Predicting gas–particle partitioning coefficients of atmospheric molecules with machine learning Atmospheric Chemistry and Physics DOI 10.5194/acp-21-13227-2021 22 October 2021 The study of climate change relies on climate models, which require an understanding of aerosol formation. We train a machine-learning model to predict the partitioning coefficients of atmospheric molecules, which govern condensation into aerosols. The model can make instant predictions based on molecular structures with accuracy surpassing that of standard computational methods. This will allow the screening of low-volatility molecules that contribute most to aerosol formation. Read more
From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models Hydrology and Earth System Sciences DOI 10.5194/hess-25-4835-2021 20 October 2021 Root water uptake is an important process in the terrestrial water cycle. How this process depends on soil water content, root distributions, and root properties is a soil–root hydraulic problem. We compare different approaches to implementing root hydraulics in macroscopic soil water flow and land surface models. Read more
Opinion: The germicidal effect of ambient air (open-air factor) revisited Atmospheric Chemistry and Physics DOI 10.5194/acp-21-13011-2021 18 October 2021 The term open-air factor was coined in the 1960s, establishing that rural air had powerful germicidal properties possibly resulting from immediate products of the reaction of ozone with alkenes, unsaturated compounds ubiquitously present in natural and polluted environments. We have re-evaluated those early experiments, applying the recently substantially improved knowledge, and put them into the context of the lifetime of aerosol-borne pathogens that are so important in the Covid-19 pandemic. Read more
The prediction of floods in Venice: methods, models and uncertainty (review article) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-2679-2021 15 October 2021 The city of Venice relies crucially on a good storm surge forecast to protect its population and cultural heritage. In this paper, we provide a state-of-the-art review of storm surge forecasting, starting from examples in Europe and focusing on the Adriatic Sea and the Lagoon of Venice. We discuss the physics of storm surge, as well as the particular aspects of Venice and new techniques in storm surge modeling. We also give recommendations on what a future forecasting system should look like. Read more
Extreme floods of Venice: characteristics, dynamics, past and future evolution (review article) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-2705-2021 13 October 2021 In this review we describe the factors leading to the extreme water heights producing the floods of Venice. We discuss the different contributions, their relative importance, and the resulting compound events. We highlight the role of relative sea level rise and the observed past and very likely future increase in extreme water heights, showing that they might be up to 160 % higher at the end of the 21st century than presently. Read more