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Snow avalanche detection and mapping in multitemporal and multiorbital radar images from TerraSAR-X and Sentinel-1

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-20-1783-2020
2 July 2020

To assess snow avalanche mapping with radar satellites in Switzerland, we compare 2 m resolution TerraSAR-X images, 10 m resolution Sentinel-1 images, and optical 1.5 m resolution SPOT-6 images. We found that radar satellites provide a valuable option to map at least larger avalanches, though avalanches are mapped only partially. By combining multiple orbits and polarizations from S1, we achieved mapping results of quality almost comparable to single high-resolution TerraSAR-X images.

Towards an objective assessment of climate multi-model ensembles – a casestudy: the Senegalo-Mauritanian upwelling region

The most robust representation of climate is usually obtained by averaging a large number of simulations, thereby cancelling individual model errors. Here, we work towards an objective way of selecting the least biased models over a certain region, based on physical parameters. This statistical method based on a neural classifier and multi-correspondence analysis is illustrated here for the Senegalo-Mauritanian region, but it could potentially be developed for any other region or process.

Modelling the potential impacts of the recent, unexpected increase in CFC-11 emissions on total column ozone recovery

The Montreal Protocol was agreed in 1987 to limit and then stop the production of man-made CFCs, which destroy stratospheric ozone. As a result, the atmospheric abundances of CFCs are now declining in the atmosphere. However, the atmospheric abundance of CFC-11 is not declining as expected under complete compliance with the Montreal Protocol. Using the UM-UKCA chemistry–climate model, we explore the impact of future unregulated production of CFC-11 on ozone recovery.

Changes of the Arctic marginal ice zone during the satellite era

It is well known that the Arctic sea ice extent is declining, and it is often assumed that the marginal ice zone (MIZ), the area of partial sea ice cover, is consequently increasing. However, we find no trend in the MIZ extent during the last 40 years from observations that is consistent with a widening of the MIZ as it moves northward. Differences of MIZ extent between different satellite retrievals are too large to provide a robust basis to verify model simulations of MIZ extent.

Is there warming in the pipeline? A multi-model analysis of the Zero Emissions Commitment from CO2

The Zero Emissions Commitment (ZEC) is the change in global temperature expected to occur following the complete cessation of CO ₂ emissions. Here we use 18 climate models to assess the value of ZEC. For our experiment we find that ZEC 50 years after emissions cease is between −0.36 to +0.29 °C. The most likely value of ZEC is assessed to be close to zero. However, substantial continued warming for decades or centuries following cessation of CO ₂ emission cannot be ruled out.

RainNet v1.0: a convolutional neural network for radar-based precipitation nowcasting

In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting, which was trained to predict continuous precipitation intensities at a lead time of 5 min. RainNet significantly outperformed the benchmark models at all lead times up to 60 min. Yet, an undesirable property of RainNet predictions is the level of spatial smoothing. Obviously, RainNet learned an optimal level of smoothing to produce a nowcast at 5 min lead time.

Changing global cropping patterns to minimize national blue water scarcity

Previous studies on water saving through food trade focussed either on comparing water productivities among countries or on analysing food trade in relation to national water endowments. Here, we consider, for the first time, both differences in water productivities and water endowments to analyse national comparative advantages. Our study reveals that blue water scarcity can be reduced to sustainable levels by changing cropping patterns while maintaining current levels of global production.

New observations of the distribution, morphology and dissolution dynamics of cryogenic gypsum in the Arctic Ocean

Based on an observed omnipresence of gypsum crystals, we concluded that their release from melting sea ice is a general feature in the Arctic Ocean. Individual gypsum crystals sank at more than 7000 m d ⁻¹ , suggesting that they are an important ballast mineral. Previous observations found gypsum inside phytoplankton aggregates at 2000 m depth, supporting gypsum as an important driver for pelagic-benthic coupling in the ice-covered Arctic Ocean.

Induced seismicity risk analysis of the hydraulic stimulation of a geothermal well on Geldinganes, Iceland

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-20-1573-2020
16 June 2020

This study presents a first-of-its-kind pre-drilling probabilistic induced seismic risk analysis for the Geldinganes (Iceland) deep-hydraulic stimulation. The results of the assessment indicate that the individual risk within a radius of 2 km around the injection point is below the safety limits. However, the analysis is affected by a large variability due to the presence of pre-drilling deep uncertainties. This suggests the need for online risk updating during the stimulation.

Linking economic and social factors to peak flows in an agricultural watershed using socio-hydrologic modeling

We describe a socio-hydrologic model that couples an agent-based model (ABM) of human decision-making with a hydrologic model. We establish this model for a typical agricultural watershed in Iowa, USA, and simulate the evolution of large discharge events over a 47-year period under changing land use. Using this modeling approach, relationships between seemingly unrelated variables such as crop markets or crop yields and local peak flow trends are quantified.

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