Decorrelation scales for Arctic Ocean hydrography – Part I: Amerasian Basin Ocean Science DOI 10.5194/os-14-161-2018 2 March 2018 We estimated spatial and temporal decorrelation scales of temperature and salinity in the Amerasian Basin in the Arctic Ocean. The estimated scales can be applied to representation error assessment in the ocean data assimilation system for the Arctic Ocean. Read more
Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring Hydrology and Earth System Sciences DOI 10.5194/hess-22-1563-2018 1 March 2018 Understanding water infiltration in karst regions is crucial as the aquifers they host provide drinkable water for a quarter of the world’s population. We present a non-invasive tool to image hydrological processes in karst systems. At our field site, the injection of electrical current in the ground, repeated daily over a 3-year period, allowed imaging changes in the groundwater content. We show that specific geological layers control seasonal to rainfall-triggered water infiltration dynamics. ERT monitoring">Read more
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
