Sea ice dynamics in the Bransfield Strait, Antarctic Peninsula, during the past 240 years: a multi-proxy intercomparison study Climate of the Past DOI 10.5194/cp-16-2459-2020 8 January 2021 We tested the applicability of the organic biomarker IPSO 25 for sea ice reconstructions in the industrial era at the western Antarctic Peninsula. We successfully evaluated our data with satellite sea ice observations. The comparison with marine and ice core records revealed that sea ice interpretations must consider climatic and sea ice dynamics. Sea ice biomarker production is mainly influenced by the Southern Annular Mode, while the El Niño–Southern Oscillation seems to have a minor impact. Read more
Optical characterization of pure pollen types using a multi-wavelength Raman polarization lidar Atmospheric Chemistry and Physics DOI 10.5194/acp-20-15323-2020 7 January 2021 Measurements of the multi-wavelength Raman polarization lidar Polly XT have been combined with measurements of pollen type and concentration using a traditional pollen sampler at a rural forest site in Kuopio, Finland. The depolarization ratio was enhanced when there were pollen grains in the atmosphere, illustrating the potential of lidar to track pollen grains in the atmosphere. The depolarization ratio of pure pollen particles was assessed for birch and pine pollen using a novel algorithm. Read more
Combined use of Mie–Raman and fluorescence lidar observations for improving aerosol characterization: feasibility experiment Atmospheric Measurement Techniques DOI 10.5194/amt-13-6691-2020 6 January 2021 To study the feasibility of a fluorescence lidar for aerosol characterization, the fluorescence channel is added to the multiwavelength Mie-Raman lidar of Lille University. A part of the fluorescence spectrum is selected by the interference filter of 44 nm bandwidth centered at 466 nm. Such an approach has demonstrated high sensitivity, allowing fluorescence signals from weak aerosol layers to be detected. The technique can also be used for monitoring the aerosol inside the cloud layers. Read more
The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – theoretical framework Atmospheric Chemistry and Physics DOI 10.5194/acp-20-15247-2020 5 January 2021 A novel lidar method to study cloud microphysical properties (of liquid water clouds) and to study aerosol–cloud interaction (ACI) is developed and presented in this paper. In Part 1, the theoretical framework including an error analysis is given together with an overview of the aerosol information that the same lidar system can obtain. The ACI concept based on aerosol and cloud information is also explained. Applications of the proposed approach to lidar measurements are presented in Part 2. Read more
Evolution of events before and after the 17 June 2017 rock avalanche at Karrat Fjord, West Greenland – a multidisciplinary approach to detecting andlocating unstable rock slopes in a remote Arctic area Earth Surface Dynamics DOI 10.5194/esurf-8-1021-2020 4 January 2021 The 17 June 2017 Karrat landslide in Greenland caused a tsunami that killed four people. We apply a multidisciplinary workflow to reconstruct a timeline of events and find that three historic landslides occurred in 2009, 2016, and 2017. We also find evidence of much older periods of landslide activity. Three newly discovered active slopes might pose a future hazard. We speculate that the trigger for the recent events is melting permafrost due to a warming climate. Read more
Iron and aluminum association with microbially processed organic matter viameso-density aggregate formation across soils: organo-metallic gluehypothesis SOIL DOI 10.5194/soil-6-597-2020 1 January 2021 Global significance of metals (extractable Fe and Al phases) to control organic matter (OM) in recognized. Next key questions include the identification of their localization and mechanism behind OM–metal relationships. Across 23 soils of contrasting mineralogy, Fe and Al phases were mainly associated with microbially processed OM as meso-density microaggregates. OM- and metal-rich nanocomposites with a narrow OM : metal ratio likely acted as binding agents. A new conceptual model was proposed. Read more
The Antarctic sea ice cover from ICESat-2 and CryoSat-2: freeboard, snow depth, and ice thickness The Cryosphere DOI 10.5194/tc-14-4453-2020 31 December 2020 Our current understanding of Antarctic ice cover is largely informed by ice extent measurements from passive microwave sensors. These records, while useful, provide a limited picture of how the ice is responding to climate change. In this paper, we combine measurements from ICESat-2 and CryoSat-2 missions to assess snow depth and ice thickness of the Antarctic ice cover over an 8-month period (April through November 2019). The potential impact of salinity in the snow layer is discussed. Read more
The catastrophic thermokarst lake drainage events of 2018 in northwesternAlaska: fast-forward into the future The Cryosphere DOI 10.5194/tc-14-4279-2020 30 December 2020 In summer 2018, northwestern Alaska was affected by widespread lake drainage which strongly exceeded previous observations. We analyzed the spatial and temporal patterns with remote sensing observations, weather data and lake-ice simulations. The preceding fall and winter season was the second warmest and wettest on record, causing the destabilization of permafrost and elevated water levels which likely led to widespread and rapid lake drainage during or right after ice breaku Read more
Focus on glaciers: a geo-photo exposition of vanishing beauty Geoscience Communication DOI 10.5194/gc-3-381-2020 29 December 2020 We organized an exhibition on the climate crisis using high-quality images shot by scientists, who are amateur photographers, during their campaigns in glacier regions. Working-age people, attracted by the gorgeous images, received the message that such beauty is in danger of vanishing. Twice, the visitors could talk directly with the experts to discuss geoscience, photography, and aesthetic choices and, of course, climate change, a problem that each of us has to play a part in to solve. Read more
Investigating the sensitivity of soil heterotrophic respiration to recent snow cover changes in Alaska using a satellite-based permafrost carbon model Biogeosciences DOI 10.5194/bg-17-5861-2020 28 December 2020 We developed a 1 km satellite-data-driven permafrost carbon model to evaluate soil respiration sensitivity to recent snow cover changes in Alaska. Results show earlier snowmelt enhances growing-season soil respiration and reduces annual carbon uptake, while early cold-season soil respiration is linked to the number of snow-free days after the land surface freezes. Our results also show nonnegligible influences of subgrid variability in surface conditions on model-simulated CO 2 seasonal cycles. Read more
A systematic exploration of satellite radar coherence methods for rapid landslide detection Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-3197-2020 25 December 2020 Satellite radar could provide information on landslide locations within days of an earthquake or rainfall event anywhere on Earth, but until now there has been a lack of systematic testing of possible radar methods, and most methods have been demonstrated using a single case study event and data from a single satellite sensor. Here we test five methods on four events, demonstrating their wide applicability and making recommendations on when different methods should be applied in the future. Read more
New flood frequency estimates for the largest river in Norway based on the combination of short and long time series Hydrology and Earth System Sciences DOI 10.5194/hess-24-5595-2020 24 December 2020 We combine systematic, historical, and paleo information to obtain flood information from the last 10 300 years for the Glomma River in Norway. We identify periods with increased flood activity (4000–2000 years ago and the recent 1000 years) that correspond broadly to periods with low summer temperatures and glacier growth. The design floods in Glomma were more than 20 % higher during the 18th century than today. We suggest that trends in flood variability are linked to snow in late spring. Read more
Tectonic exhumation of the Central Alps recorded by detrital zircon in theMolasse Basin, Switzerland Solid Earth DOI 10.5194/se-11-2197-2020 23 December 2020 We present new U–Pb age data to provide insights into the source of sediment for the Molasse Sedimentary Basin in Switzerland. The paper aims to help shed light on the processes that built the Central Alpine Mountains between ~35 and ~15 Ma. A primary conclusion drawn from the results is that at ~21 Ma there was a significant change in the sediment sources for the basin. We feel this change indicates major tectonic changes within the Central Alps. Read more
Evaluation of Arctic warming in mid-Pliocene climate simulations Climate of the Past DOI 10.5194/cp-16-2325-2020 22 December 2020 The simulations for the past climate can inform us about the performance of climate models in different climate scenarios. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), when the CO 2 level was comparable to today. The results highlight the importance of slow feedbacks in the model simulations and imply that we must be careful when using simulations of the mPWP as an analogue for future climate change. Read more
Sensitivity of the Southern Hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistry Atmospheric Chemistry and Physics DOI 10.5194/acp-20-14043-2020 21 December 2020 Ozone depletion over Antarctica was shown to influence the tropospheric jet in the Southern Hemisphere. We investigate the atmospheric response to ozone depletion comparing climate model ensembles with interactive and prescribed ozone fields. We show that allowing feedbacks between ozone chemistry and model physics as well as including asymmetries in ozone leads to a strengthened ozone depletion signature in the stratosphere but does not significantly affect the tropospheric jet position. Read more
Distinguishing the impacts of ozone and ozone-depleting substanceson the recent increase in Antarctic surface mass balance The Cryosphere DOI 10.5194/tc-14-4135-2020 18 December 2020 The increase in Antarctic surface mass balance (SMB, precipitation vs. evaporation/sublimation) is projected to mitigate sea-level rise. Here we show that nearly half of this increase over the 20th century is attributed to stratospheric ozone depletion and ozone-depleting substance (ODS) emissions. Our results suggest that the phaseout of ODS by the Montreal Protocol, and the recovery of stratospheric ozone, will act to decrease the SMB over the 21st century and the mitigation of sea-level rise. Read more
Earth Girl Volcano: characterizing and conveying volcanic hazard complexity in an interactive casual game of disaster preparedness and response Geoscience Communication DOI 10.5194/gc-3-343-2020 17 December 2020 Earth Girl Volcano is a casual strategy interactive game about saving communities at risk of volcanic hazards. The easy-to-play game features a friendly animated visual style and an engaging simulation of volcanic events. The game was designed by a multidisciplinary team to appeal to mainstream non-technical audiences, and it was inspired by the experiences of disaster survivors and civil defense teams. Players can learn through gameplay about disaster preparedness and response. Read more
The baseline wander correction based on the improved ensemble empirical mode decomposition (EEMD) algorithm for groundedelectrical source airborne transient electromagnetic signals Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-9-443-2020 16 December 2020 The baseline wander has special characteristics, such as being low frequency, large amplitude, non-periodic, and non-stationary. It is caused by the receiving coil motion and always exists in the process of data acquisition. The proposed method can be used to solve similar problems. This paper has the following highlights: (1) the method can be used to process non-periodic and non-stationary signals; (2) the method is adaptive to satisfy the stopping criterion based on the measured signal. Read more
Millennial-scale atmospheric CO2 variations during the Marine Isotope Stage 6 period (190–135 ka) Climate of the Past DOI 10.5194/cp-16-2203-2020 15 December 2020 We reconstruct atmospheric CO 2 from the EPICA Dome C ice core during Marine Isotope Stage 6 (185–135 ka) to understand carbon mechanisms under the different boundary conditions of the climate system. The amplitude of CO 2 is highly determined by the Northern Hemisphere stadial duration. Carbon dioxide maxima show different lags with respect to the corresponding abrupt CH 4 jumps, the latter reflecting rapid warming in the Northern Hemisphere. Read more
Reduced global warming from CMIP6 projections when weighting models by performance and independence Earth System Dynamics DOI 10.5194/esd-11-995-2020 14 December 2020 In this study, we weight climate models by their performance with respect to simulating aspects of historical climate and their degree of interdependence. Our method is found to increase projection skill and to correct for structurally similar models. The weighted end-of-century mean warming (2081–2100 relative to 1995–2014) is 3.7 °C with a likely (66 %) range of 3.1 to 4.6 °C for the strong climate change scenario SSP5-8.5; this is a reduction of 0.4 °C compared with the unweighted mean. Read more