Brief communication: Glaciers in the Hunza catchment (Karakoram) have been nearly in balance since the 1970s The Cryosphere DOI 10.5194/tc-11-531-2017 15 February 2017 Previous geodetic estimates of glacier mass changes in the Karakoram have revealed balanced budgets or a possible slight mass gain since the year ∼ 2000. We used old US reconnaissance imagery and could show that glaciers in the Hunza River basin (Central Karakoram) experienced on average no significant mass changes also since the 1970s. Likewise the glaciers had heterogeneous behaviour with frequent surge activities during the last 40 years. Read more
Trend of atmospheric mercury concentrations at Cape Point for 1995–2004 and since 2007 Atmospheric Chemistry and Physics DOI 10.5194/acp-17-2393-2017 15 February 2017 Currently the Cape Point GAW GEM record is a very sought-after data record for international modelers and scientist alike, as the data set of 20 years represents the longest record in the Southern Hemisphere (SH). CPT was the only monitoring site on the African continent and one of eight GMOS ground-based monitoring sites located in the SH. The increasing Hg trend observed at CPT is of global importance as treaties such as the Minamata Convention on Mercury is there to combat Hg pollution. Read more
Rapid attribution of the August 2016 flood-inducing extreme precipitation in south Louisiana to climate change Hydrology and Earth System Sciences DOI 10.5194/hess-21-897-2017 14 February 2017 During August 2016, heavy precipitation led to devastating floods in south Louisiana, USA. Here, we analyze the climatological statistics of the precipitation event, as defined by its 3-day total over 12–14 August. Using observational data and high-resolution global coupled model experiments, we find for a comparable event on the central US Gulf Coast an average return period of about 30 years and the odds being increased by at least 1.4 since 1900 due to anthropogenic climate change. Read more
Global scale variability of the mineral dust long-wave refractive index: a new dataset of in situ measurements for climate modeling and remote sensing Atmospheric Chemistry and Physics DOI 10.5194/acp-17-1901-2017 9 February 2017 Modeling the interaction of dust with long-wave (LW) radiation is still a challenge due to the scarcity of information on their refractive index. In this paper, we present a unique dataset of dust refractive indices obtained from in situ measurements in a large smog chamber. Our results show that the dust LW refractive index varies strongly from source to source due to particle composition changes. We recommend taking this variability into account in climate and remote sensing applications. Read more
Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica The Cryosphere DOI 10.5194/tc-11-451-2017 8 February 2017 In this paper we investigate elevation changes of Thwaites Glacier, West Antarctica, one of the main sources of excess ice discharge into the ocean. We find that in early 2013, four subglacial lakes separated by 100 km drained suddenly, discharging more than 3 km3of water under the fastest part of the glacier in less than 6 months. Concurrent ice-speed measurements show only minor changes, suggesting that ice dynamics are not strongly sensitive to changes in water flow. Read more
A joint thermal and electromagnetic diagnostics approach for the inspection of thick walls Geoscientific Instrumentation, Methods and Data Systems DOI 10.5194/gi-6-81-2017 8 February 2017 A numerical inversion approach to detect and localize inclusions in thick walls under quasi-periodic natural solicitations is presented. It is based on a preliminary analysis of surface temperature field evolution with time. This analysis is improved by taking advantage of a priori information provided by ground-penetrating radar reconstructions. In this way, it is possible to improve the accuracy of the images achievable with the stand-alone thermal reconstruction method. Read more
A high-altitude balloon experiment to probe stratospheric electric fields from low latitudes Annales Geophysicae DOI 10.5194/angeo-35-189-2017 3 February 2017 Results from a high-altitude balloon experiment conducted from a low-latitude station in India are presented in this work. The objectives of this experiment were to probe and understand the processes driving the various electric field sources at low latitudes. During this experiment, electric fields in the range of 5–6 mV m−1 were observed at the balloon float altitude of 35 km. Atmospheric waves of few 100 km horizontal wavelength are suggested to be a potential source of these electric fields. Read more
Halogen chemistry reduces tropospheric O3 radiative forcing Atmospheric Chemistry and Physics DOI 10.5194/acp-17-1557-2017 31 January 2017 We model pre-industrial to present day changes using the GEOS-Chem global chemical transport model with halogens (Cl, Br, I). The model better captures pre-industrial O3observations with halogens included. Halogens buffer the tropospheric forcing of O3(RFTO[~3~]) from pre-industrial to present day, reducing RFTO[~3~]by 0.087 Wm−2. This reduction is greater than that from halogens on stratospheric O3(−0.05 Wm−2). This suggests that models that do not include halogens will overestimate RFTO[~3~]by ~ 25%. Read more
Decadal changes in global surface NOx emissions from multi-constituent satellite data assimilation Atmospheric Chemistry and Physics DOI 10.5194/acp-17-807-2017 27 January 2017 Global surface emissions of nitrogen oxides (NOx) over a 10-year period (2005–2014) are estimated from assimilation of multiple satellite datasets. We present detailed distributions of the estimated NOxemission distributions for all major regions, the diurnal, seasonal, and decadal variability. The estimated emissions show a positive trend over India, China, and the Middle East, and a negative trend over the United States, southern Africa, and western Europe. Read more
Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation The Cryosphere DOI 10.5194/tc-11-217-2017 27 January 2017 Based on DEM simulations we developed a new model for the onset of crack propagation in snow slab avalanche release. The model reconciles past approaches by considering the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The model agrees with extensive field data and can reproduce crack propagation on low-angle terrain and the decrease in critical crack length with increasing slope angle observed in numerical experiments. Read more