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
Venice flooding and sea level: past evolution, present issues, and future projections (introduction to the special issue) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-2633-2021 11 October 2021 Venice is an iconic place, and a paradigm of huge historical and cultural value is at risk. The threat posed by floods has dramatically increased in recent decades and is expected to continue to grow – and even accelerate – through this century. There is a need to better understand the future evolution of the relative sea level and its extremes and to develop adaptive planning strategies appropriate for present uncertainty, which might not be substantially reduced in the near future. Read more
Sea-level rise in Venice: historic and future trends (review article) Natural Hazards and Earth System Sciences DOI 10.5194/nhess-21-2643-2021 8 October 2021 Relative sea level in Venice rose by about 2.5 mm/year in the past 150 years due to the combined effect of subsidence and mean sea-level rise. We estimate the likely range of mean sea-level rise in Venice by 2100 due to climate changes to be between about 10 and 110 cm, with an improbable yet possible high-end scenario of about 170 cm. Projections of subsidence are not available, but historical evidence demonstrates that they can increase the hazard posed by climatically induced sea-level rise. Read more
