The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf The Cryosphere DOI 10.5194/tc-14-2173-2020 16 July 2020 In October 2019 the research vessel Polarstern was moored to an ice floe in order to travel with it on the 1-year-long MOSAiC journey through the Arctic. Here we provide historical context of the floe’s evolution and initial state for upcoming studies. We show that the ice encountered on site was exceptionally thin and was formed on the shallow Siberian shelf. The analyses presented provide the initial state for the analysis and interpretation of upcoming biogeochemical and ecological studies. Read more
The enigmatic curvature of Central Iberia and its puzzling kinematics Solid Earth DOI 10.5194/se-11-1247-2020 16 July 2020 Pangea was assembled during Devonian to early Permian times and resulted in a large-scale and winding orogeny that today transects Europe, northwestern Africa, and eastern North America. This orogen is characterized by an S shape corrugated geometry in Iberia. This paper presents the advances and milestones in our understanding of the geometry and kinematics of the Central Iberian curve from the last decade with particular attention paid to structural and paleomagnetic studies. Read more
Landfast sea ice material properties derived from ice bridge simulations using the Maxwell elasto-brittle rheology The Cryosphere DOI 10.5194/tc-14-2137-2020 14 July 2020 We study the formation of ice arches between two islands using a model that resolves crack initiation and propagation. This model uses a damage parameter to parameterize the presence or absence of cracks in the ice. We find that the damage parameter allows for cracks to propagate in the ice but in a different orientation than predicted by theory. The results call for improvement in how stress relaxation associated with this damage is parameterized. Read more
Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections Biogeosciences DOI 10.5194/bg-17-3439-2020 14 July 2020 We assess 21st century projections of marine biogeochemistry in the CMIP6 Earth system models. These models represent the most up-to-date understanding of climate change. The models generally project greater surface ocean warming, acidification, subsurface deoxygenation, and euphotic nitrate reductions but lesser primary production declines than the previous generation of models. This has major implications for the impact of anthropogenic climate change on marine ecosystems. Read more
Lower-thermosphere response to solar activity: an empirical-mode-decomposition analysis of GOCE 2009–2012 data Annales Geophysicae DOI 10.5194/angeo-38-789-2020 9 July 2020 Forecasting the thermosphere (atmosphere’s uppermost layer from 90 to 800 km altitude) is crucial to space mission design, spacecraft operations and space surveillance. The thermosphere is controlled by the Sun through variable solar extreme-ultraviolet radiation and the solar wind. We show how the solar indices Mg II and Ap may be used in forecasting thermospheric density at 260 km, a very low altitude, where the GOCE satellite operated from 2009 to 2013, during the full rise of solar cycle 24. GOCE 2009–2012 data">Read more
Identifying a regional aerosol baseline in the eastern North Atlantic using collocated measurements and a mathematical algorithm to mask high-submicron-number-concentration aerosol events Atmospheric Chemistry and Physics DOI 10.5194/acp-20-7553-2020 9 July 2020 Continuous high-time-resolution ambient data can include periods when aerosol properties do not represent regional aerosol processes due to high-concentration local events. We develop a novel aerosol mask at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) facility in the eastern North Atlantic (ENA). We use two ground sites to validate the mask, include a comparison with aircraft overflights, and provide guidance to increase data quality at ENA and other locations. Read more
The contribution of microbial communities in polymetallic nodules to thediversity of the deep-sea microbiome of the Peru Basin (4130–4198 mdepth) Biogeosciences DOI 10.5194/bg-17-3203-2020 7 July 2020 Industrial-scale mining of deep-sea polymetallic nodules will remove nodules in large areas of the sea floor. We describe community composition of microbes associated with nodules of the Peru Basin. Our results show that nodules provide a unique ecological niche, playing an important role in shaping the diversity of the benthic deep-sea microbiome and potentially in element fluxes. We believe that our findings are highly relevant to expanding our knowledge of the impact associated with mining. Read more
Enhanced growth rate of atmospheric particles from sulfuric acid Atmospheric Chemistry and Physics DOI 10.5194/acp-20-7359-2020 7 July 2020 Sulfuric acid is a major atmospheric vapour for aerosol formation. If new particles grow fast enough, they can act as cloud droplet seeds or affect air quality. In a controlled laboratory set-up, we demonstrate that van der Waals forces enhance growth from sulfuric acid. We disentangle the effects of ammonia, ions and particle hydration, presenting a complete picture of sulfuric acid growth from molecular clusters onwards. In a climate model, we show its influence on the global aerosol budget. Read more
The role of prior assumptions in carbon budget calculations Earth System Dynamics DOI 10.5194/esd-11-563-2020 2 July 2020 Levels of future temperature change are often used interchangeably with carbon budget allowances in climate policy, a relatively robust relationship on the timescale of this century. However, recent advances in understanding underline that continued warming after net-zero emissions have been achieved cannot be ruled out by observations of warming to date. We consider here how such behavior could be constrained and how policy can be framed in the context of these uncertainties. Read more
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. Read more
