Ensemble models from machine learning: an example of wave runup and coastal dune erosion Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2295-2019 29 October 2019 Wave runup is important for characterizing coastal vulnerability to wave action; however, it is complex and uncertain to predict. We use machine learning with a high-resolution dataset of wave runup to develop an accurate runup predictor that includes prediction uncertainty. We show how uncertainty in wave runup predictions can be used practically in a model of dune erosion to make ensemble predictions that provide more information and greater predictive skill than a single deterministic model. Read more
Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions? Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2249-2019 11 October 2019 Here we evaluate geologic, geomorphic, and anthropogenic controls on rockfall hazard and highlight the complexity of interpreting future rockfall hazard based on former boulder distributions. To evaluate how past rockfall deposits relate to contemporary rockfall hazard, we mapped then compared the locations, physical characteristics, and lithologies of rockfall boulders deposited during the 2010–2011 Canterbury earthquake sequence (n= 185) with their prehistoric counterparts (n= 1093). Read more
Relative impact of aerosol, soil moisture, and orography perturbations on deep convection Atmospheric Chemistry and Physics DOI 10.5194/acp-19-12343-2019 7 October 2019 This study addresses the relative impact of orography, soil moisture, and aerosols on precipitation over Germany in different weather regimes. We find that the impact of these perturbations is higher for weak than for strong large-scale forcing. Furthermore, aerosols and soil moisture are both of similar importance for precipitation forecasting, which indicates that their inclusion in operational ensemble forecasting should be assessed in the future. Read more
Mapping landscape connectivity as a driver of species richness under tectonic and climatic forcing Earth Surface Dynamics DOI 10.5194/esurf-7-895-2019 1 October 2019 Mountainous landscapes have long been recognized as potential drivers for genetic drift, speciation, and ecological resilience. We present a novel approach that can be used to assess and quantify drivers of biodiversity, speciation, and endemism over geological time. Using coupled climate–landscape models, we show that biodiversity under tectonic and climatic forcing relates to landscape dynamics and that landscape complexity drives species richness through orogenic history. Read more
Understanding the spatiotemporal development of human settlement in hurricane-prone areas on the US Atlantic and Gulf coasts using nighttime remote sensing Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2141-2019 1 October 2019 This study examined the spatiotemporal dynamics of nighttime satellite-derived human settlement in response to different levels of hurricane proneness in a period from 1992 to 2013. It confirms theSnow Belt-to-Sun BeltUS population shift trend. The results also suggest that hurricane-exposed human settlement has grown in extent and area, as more hurricane exposure has experienced a larger increase rate in settlement intensity. Read more
Benchmarking the predictive capability of hydrological models for river flow and flood peak predictions across over 1000 catchments in Great Britain Hydrology and Earth System Sciences DOI 10.5194/hess-23-4011-2019 30 September 2019 We evaluated four hydrological model structures and their parameters on over 1100 catchments across Great Britain, considering modelling uncertainties. Models performed well for most catchments but failed in parts of Scotland and south-eastern England. Failures were often linked to inconsistencies in the water balance. This research shows what conceptual lumped models can achieve, gives insights into where and why these models may fail, and provides a benchmark of national modelling capability. Read more
Physical constraints for respiration in microbial hotspots in soil and their importance for denitrification Biogeosciences DOI 10.5194/bg-16-3665-2019 27 September 2019 A combination of gas chromatography and X-ray CT reveals the microscale processes that govern soil respiration. Aerobic and anaerobic respiration in microbial hotspots depends not only on the quality and quantity of soil organic matter, but also on the spatial distribution of hotspots. Denitrification kinetics are mainly governed by hotspot architecture due to local competition for oxygen during growth. Cumulative behavior is mainly governed by water saturation due to the overall supply with O2. Read more
Estimating Greenland tidewater glacier retreat driven by submarine melting The Cryosphere DOI 10.5194/tc-13-2489-2019 26 September 2019 The ocean’s influence on the retreat of Greenland’s tidewater glaciers is a key factor determining future sea level. By considering observations of ~200 glaciers from 1960, we find a significant relationship between retreat and melting in the ocean. Projected forwards, this relationship estimates the future evolution of Greenland’s tidewater glaciers and provides a practical and empirically validated way of representing ice–ocean interaction in large-scale models used to estimate sea level rise. Read more
Global-scale human pressure evolution imprints on sustainability of river systems Hydrology and Earth System Sciences DOI 10.5194/hess-23-3933-2019 25 September 2019 A simple and effective index for the quantitative estimation of the evolution of human pressure on rivers at global scale is proposed. This index, based on nightlights and river discharge data, shows a significant increase from 1992 to 2013 worldwide. The most notable changes are found in river basins across Africa and Asia, where human pressure on rivers is growing markedly. This index identifies priority areas that can be targeted for the implementation of mitigation strategies and plans. Read more
Hybrid-Vlasov modelling of nightside auroral proton precipitation during southward interplanetary magnetic field conditions Annales Geophysicae DOI 10.5194/angeo-37-791-2019 10 September 2019 When the terrestrial magnetic field is disturbed, particles from the near-Earth space can precipitate into the upper atmosphere. This work presents, for the first time, numerical simulations of proton precipitation in the energy range associated with the production of aurora (∼1–30 keV) using a global kinetic model of the near-Earth space: Vlasiator. We find that nightside proton precipitation can be regulated by the transition region between stretched and dipolar geomagnetic field lines. Read more