On the seasonal variation in observed size distributions in northern Europe and their changes with decreasing anthropogenic emissions in Europe: climatology and trend analysis based on 17 years of data from Aspvreten, Sweden Atmospheric Chemistry and Physics DOI 10.5194/acp-19-14849-2019 17 December 2019 In this study we explore 17 years of aerosol number size distribution data (10–390 nm) observed at Aspvreten (58.8° N, 17.4° E, 25 m a.s.l.). The station, located in northern Europe, is representative of rural background conditions. The study focused on identifying trends in aerosol number size distribution properties. The study shows that total number has decreased by 30 % and aerosol submicron mass by 50 % on average. Observed trends vary strongly with both season and particle size. Read more
Stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis of microfractured Hadean zircon Geochronology DOI 10.5194/gchron-1-85-2019 17 December 2019 The oldest known minerals on Earth are Hadean (> 4.0 Ga) zircons from the Jack Hills, Australia. We present the first application to such Hadean zircons of stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis (stepwise CA-ID-TIMS-TEA). We examine the evolution in the U–Pb age and trace element chemistry of zircon domains accessed by successive chemical abrasion steps in the context of the geologic history of the Jack Hills zircons. Read more
Societal breakdown as an emergent property of large-scale behavioural models of land use change Earth System Dynamics DOI 10.5194/esd-10-809-2019 10 December 2019 Concerns are growing that human activity will lead to social and environmental breakdown, but it is hard to anticipate when and where such breakdowns might occur. We developed a new model of land management decisions in Europe to explore possible future changes and found that decision-making that takes into account social and environmental conditions can produce unexpected outcomes that include societal breakdown in challenging conditions. Read more
First reported case of thunderstorm asthma in Israel Natural Hazards and Earth System Sciences DOI 10.5194/nhess-19-2715-2019 10 December 2019 During severe thunderstorms, cold outflows can eject pollen and dust particles from the surface, releasing allergens and causingthunderstorm asthmaepidemics in sensitive populations. We report the first case in Israel that occurred on 25 October 2015. The emergency room presentation records from three hospitals in central Israel showed a clear increase in patients with respiratory complaints immediately after the passage of a massive super-cell thunderstorm in the area. Read more
The diurnal cycle of the smoky marine boundary layer observed during August in the remote southeast Atlantic Atmospheric Chemistry and Physics DOI 10.5194/acp-19-14493-2019 10 December 2019 Boundary layer (BL) semi-direct effects in the remote SE Atlantic are investigated using LASIC field measurements and satellite retrievals. Low-cloud cover and cloud liquid water path decrease with increasing smoke loadings in the BL. Daily-mean surface-based mixed layer is warmer by 0.5 K, moisture accumulates near the surface throughout the night, and the BL deepens by 200 m, with LWPs and cloud top heights increasing, in the sunlit morning hours, as part of the smoke-altered BL diurnal cycle. Read more
Can we use sea surface temperature and productivity proxy records to reconstruct Ekman upwelling? Climate of the Past DOI 10.5194/cp-15-1985-2019 10 December 2019 We test two assumptions that are often made in paleoclimate studies by using observations and ask whether temperature and productivity proxy records in the Southern California Current can be used to reconstruct Ekman upwelling. By examining the covariation between alongshore wind stress, temperature, and productivity, we found that the dominant covarying pattern does not reflect Ekman upwelling. Other upwelling patterns found are timescale dependent. Multiple proxies can improve reconstruction. Read more
Large-scale particulate air pollution and chemical fingerprint of volcanic sulfate aerosols from the 2014–2015 Holuhraun flood lava eruption of Bárðarbunga volcano (Iceland) Atmospheric Chemistry and Physics DOI 10.5194/acp-19-14253-2019 3 December 2019 This study, benefiting especially from recently developed mass spectrometry observations of aerosols, highlights unknown properties of volcanic sulfates in the troposphere. It shows their specific chemical fingerprint, distinct from those of freshly emitted industrial sulfates and background aerosols. We also demonstrate the large-scale persistence of the volcanic sulfate pollution over weeks. Hence, these results cast light on the impact of tropospheric eruptions on air quality and climate. Read more
Low-temperature triple-capillary cryostat for ice crystal growth studies Atmospheric Measurement Techniques DOI 10.5194/amt-12-6143-2019 3 December 2019 We have built a triple-capillary cryostat designed to reduce potential instrumental effects that may have influenced earlier measurements and to improve our understanding of the processes responsible for ice crystal shapes and sizes. In this cryostat, a crystal forms on one of three well-separated and ultrafine capillaries. In this paper we describe the new instrument and present several observations made using the instrument to illustrate the instrument’s advantages. Read more
Compacting the description of a time-dependent multivariable system and its multivariable driver by reducing the state vectors to aggregate scalars: the Earth’s solar-wind-driven magnetosphere Nonlinear Processes in Geophysics DOI 10.5194/npg-26-429-2019 3 December 2019 A methodology is developed to simplify the mathematical description of activity in a time-dependent driven system. The method describes the response in the system that is most-closely related to the driver. This reduced description has advantages: low noise, high prediction efficiency, linearity in the described system response to the driver, and compactness. The analysis of the Earth’s magnetospheric system is demonstrated. Read more
Distinct stores and the routing of water in the deep critical zone of a snow-dominated volcanic catchment Hydrology and Earth System Sciences DOI 10.5194/hess-23-4661-2019 3 December 2019 This paper examines the influence of the subsurface structure on water routing, water residence times, and the hydrologic response of distinct groundwater stores and further investigates their contribution to streamflow. We conclude that deep groundwater from the fractured aquifer system, rather than shallow groundwater, is the dominant source of streamflow, which highlights the need to better characterize the deep subsurface of mountain systems using interdisciplinary studies such as this one. Read more
