The European mountain cryosphere: a review of its current state, trends, and future challenges The Cryosphere DOI 10.5194/tc-12-759-2018 1 March 2018 This paper makes a rather exhaustive overview of current knowledge of past, current, and future aspects of cryospheric issues in continental Europe and makes a number of reflections of areas of uncertainty requiring more attention in both scientific and policy terms. The review paper is completed by a bibliography containing 350 recent references that will certainly be of value to scholars engaged in the fields of glacier, snow, and permafrost research. Read more
The maintenance of elevated active chlorine levels in the Antarctic lower stratosphere through HCl null cycles Atmospheric Chemistry and Physics DOI 10.5194/acp-18-2985-2018 1 March 2018 This paper revisits the chemistry leading to strong ozone depletion in the Antarctic. We focus on the heart of the ozone layer in the lowermost stratosphere in the core of the vortex. We argue that chemical cycles (referred to as HCl null cycles) that have hitherto been largely neglected counteract the deactivation of chlorine and are therefore key to ozone depletion in the core of the Antarctic vortex. The key process to full activation of chlorine is the photolysis of formaldehyde. Read more
Citizen observations contributing to flood modelling: opportunities and challenges Hydrology and Earth System Sciences DOI 10.5194/hess-22-1473-2018 28 February 2018 Citizens can contribute to science by providing data, analysing them and as such contributing to decision-making processes. For example, citizens have collected water levels from gauges, which are important when simulating/forecasting floods, where data are usually scarce. This study reviewed such contributions and concluded that integration of citizen data may not be easy due to their spatio-temporal characteristics but that citizen data still proved valuable and can be used in flood modelling. Read more
Long-term series and trends in surface solar radiation in Athens, Greece Atmospheric Chemistry and Physics DOI 10.5194/acp-18-2395-2018 19 February 2018 The National Observatory of Athens has been collecting solar radiation, sunshine duration, and cloud and visibility data/observations since the beginning of the 20th century. In this work we present surface solar radiation data since 1953 and reconstructed data since 1900. We have attempted to show and discuss the long-term changes in solar surface radiation over Athens, Greece, using these unique datasets. Read more
Total ozone trends from 1979 to 2016 derived from five merged observational datasets – the emergence into ozone recovery Atmospheric Chemistry and Physics DOI 10.5194/acp-18-2097-2018 14 February 2018 This paper commemorates the 30-year anniversary of the initial signing of the Montreal Protocol (MP) on substances that deplete the ozone layer. The MP is so far successful in reducing ozone-depleting substances, and total ozone decline was successfully stopped by the late 1990s. Total ozone levels have been mostly stable since then. In some regions, barely significant upward trends are observed that suggest an emergence into the expected ozone recovery phase. Read more
Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development Biogeosciences DOI 10.5194/bg-15-905-2018 13 February 2018 Using satellite technology and a life-size experiment, we analysed the impact of oyster reefs on mats of microscopic algae that develop within coastal mudflats. We showed that the relationship between microalgae and oysters is not limited to a one-way process where microalgae are a food source to oysters, but that oysters also promote microalgae mats development, presumably by providing nutrients to them. This might yield new insights into coastal ecosystem management. Read more
Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery Atmospheric Chemistry and Physics DOI 10.5194/acp-18-1379-2018 6 February 2018 Using a robust analysis, with artefact-corrected ozone data, we confirm upper stratospheric ozone is recovering following the Montreal Protocol, but that lower stratospheric ozone (50° S–50° N) has continued to decrease since 1998, and the ozone layer as a whole (60° S–60° N) may be lower today than in 1998. No change in total column ozone may be due to increasing tropospheric ozone. State-of-the-art models do not reproduce lower stratospheric ozone decreases. Read more
Modelling ocean-colour-derived chlorophyll a Biogeosciences DOI 10.5194/bg-15-613-2018 30 January 2018 This study provides a demonstration that a biogeochemical/ecosystem/optical computer model which explicitly captures how light is radiated at the surface of the ocean and can be used as a laboratory to explore products (such as Chla) that are derived from satellite measurements of ocean colour. It explores uncertainties that arise from data input used to derive the algorithms for the products, and issues arising from the interplay between optically important constituents in the ocean. Read more
Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin Atmospheric Chemistry and Physics DOI 10.5194/acp-18-921-2018 25 January 2018 We made airborne measurements of aerosol particle concentrations and properties over the Amazon Basin. We found extremely high concentrations of very small particles in the region between 8 and 14 km altitude all across the basin, which had been recently formed by gas-to-particle conversion at these altitudes. This makes the upper troposphere a very important source region of atmospheric particles with significant implications for the Earth’s climate system. Read more
On the link between stress field and small-scale hydraulic fracture growth in anisotropic rock derived from microseismicity Solid Earth DOI 10.5194/se-9-39-2018 25 January 2018 To characterize the stress field at the Grimsel Test Site (GTS) underground rock laboratory, a series of hydrofracturing and overcoring tests were performed. Our study demonstrates that microseismicity monitoring along with high-resolution event locations provides valuable information for interpreting stress characterization measurements. Read more
