Run-up, inundation, and sediment characteristics of the 22 December 2018 Sunda Strait tsunami, Indonesia Natural Hazards and Earth System Sciences DOI 10.5194/nhess-20-933-2020 21 April 2020 This article reports the results of a field survey carried out in the disaster area of the December 2018 Sunda Strait tsunami, Indonesia. It provides data covering run-up heights, inundations, tsunami directions, and sediment characteristics. The data can be used for the validation of hydrodynamic models, and they contribute to a better understanding of the Sunda Strait tsunami caused by the Anak Krakatau volcano. In addition, they are important for spatial planning and mitigation efforts. Read more
Supercooled liquid water cloud observed, analysed, and modelled at the top ofthe planetary boundary layer above Dome C, Antarctica Atmospheric Chemistry and Physics DOI 10.5194/acp-20-4167-2020 21 April 2020 Thin (~ 100 m) supercooled liquid water (SLW, water staying in liquid phase below 0 °C) clouds have been detected, analysed, and modelled over the Dome C (Concordia, Antarctica) station during the austral summer 2018–2019 using observations and meteorological analyses. The SLW clouds were observed at the top of the planetary boundary layer and the SLW content was always strongly underestimated by the model indicating an incorrect simulation of the surface energy budget of the Antarctic Plateau. Read more
Ramped thermal analysis for isolating biologically meaningful soil organic matter fractions with distinct residence times SOIL DOI 10.5194/soil-6-131-2020 16 April 2020 Soils contain one of the largest and most dynamic pools of carbon on Earth, yet scientists still struggle to understand the reactivity and fate of soil organic matter upon disturbance. In this study, we found that with increasing thermal stability, the turnover time of organic matter increased from decades to centuries with a concurrent shift in chemical composition. In this proof-of-concept study, we found that ramped thermal analyses can provide new insights for understanding soil carbon. Read more
Baroclinic and barotropic instabilities in planetary atmospheres: energetics, equilibration and adjustment Nonlinear Processes in Geophysics DOI 10.5194/npg-27-147-2020 16 April 2020 Baroclinic and barotropic instabilities are well known as the processes responsible for the production of the most important energy-containing eddies in the atmospheres and oceans of Earth and other planets. Linear and nonlinear instability theories provide insights into when such instabilities may occur, grow to a large amplitude and saturate, with examples from the laboratory, simplified numerical models and planetary atmospheres. We conclude with a number of open issues for future research. Read more
Description and Evaluation of the specified-dynamics experiment in the Chemistry-Climate Model Initiative Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3809-2020 9 April 2020 Atmospheric composition is strongly influenced by global-scale winds that are not always properly simulated in computer models. A common approach to correct for this bias is to relax or nudge to the observed winds. Here we systematically evaluate how well this technique performs across a large suite of chemistry–climate models in terms of its ability to reproduce key aspects of both the tropospheric and stratospheric circulations. Read more
Real-time pollen monitoring using digital holography Atmospheric Measurement Techniques DOI 10.5194/amt-13-1539-2020 9 April 2020 We present the first validation of the only operational automatic pollen monitoring system based on holography, the Swisens Poleno. The device produces real-time images of coarse aerosols, and by applying a machine learning algorithm we identify a range of pollen taxa with accuracy >90 %. The device was further validated in controlled chamber experiments to verify the counting ability and the performance of additional fluorescence measurements, which can further be used in pollen identification. Read more
Technical note: LIMS observations of lower stratospheric ozone in the southern polar springtime of 1978 Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3663-2020 7 April 2020 The Nimbus 7 limb infrared monitor of the stratosphere (LIMS) instrument operated from October 25, 1978, through May 28, 1979. This note focuses on the lower stratosphere of the southern hemisphere, subpolar regions in relation to the position of the polar vortex. Both LIMS ozone and nitric acid show reductions within the edge of the polar vortex at 46 hPa near 60° S from late October through mid-November 1978, indicating that there was a chemical loss of Antarctic ozone some weeks earlier. LIMS observations of lower stratospheric ozone in the southern polar springtime of 1978">Read more
Terrestrial methane emissions from the Last Glacial Maximum to the preindustrial period Climate of the Past DOI 10.5194/cp-16-575-2020 7 April 2020 We investigate the changes in natural methane emissions between the Last Glacial Maximum and preindustrial periods with a methane-enabled version of MPI-ESM. We consider all natural sources of methane except for emissions from wild animals and geological sources. Changes are dominated by changes in tropical wetland emissions, high-latitude wetlands play a secondary role, and all other natural sources are of minor importance. We explain the changes in ice core methane by methane emissions only. Read more
Methane emissions from the Munich Oktoberfest Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3683-2020 3 April 2020 We demonstrate for the first time that large festivals can be significant methane sources, though they are not included in emission inventories. We combined in situ measurements with a Gaussian plume model to determine the Oktoberfest emissions and show that they are not due solely to human biogenic emissions, but are instead primarily fossil fuel related. Our study provides the foundation to develop reduction policies for such events and new pathways to mitigate fossil fuel methane emissions. Read more
Deconvolution of boundary layer depth and aerosol constraints on cloud water path in subtropical stratocumulus decks Atmospheric Chemistry and Physics DOI 10.5194/acp-20-3609-2020 3 April 2020 Cloud water content and the number of droplets inside clouds covary with boundary layer depth. This covariation may amplify the change in water content due to a change in droplet number inferred from long-term observations. Taking this into account shows that the change in water content for increased droplet number in observations and high-resolution simulations agrees in shallow boundary layers. Meanwhile, deep boundary layers are under-sampled in process-scale simulations and observations. Read more
