A 305-year continuous monthly rainfall series for the island of Ireland (1711–2016) Climate of the Past DOI 10.5194/cp-14-413-2018 27 March 2018 This work reconstructs a continuous 305-year rainfall record for Ireland. The series reveals remarkable variability in decadal rainfall – far in excess of the typical period of digitised data. Notably, the series sheds light on exceptionally wet winters in the 1730s and wet summers in the 1750s. The derived record, one of the longest continuous series in Europe, offers a firm basis for benchmarking other long-term records and reconstructions of past climate both locally and across Europe. Read more
On the retrieval of sea ice thickness and snow depth using concurrent laser altimetry and L-band remote sensing data The Cryosphere DOI 10.5194/tc-12-993-2018 22 March 2018 This work proposes a new data synergy method for the retrieval of sea ice thickness and snow depth by using colocating L-band passive remote sensing and active laser altimetry. Physical models are adopted for the retrieval, including L-band radiation model and buoyancy relationship. Covariability of snow depth and total freeboard is further utilized to mitigate resolution differences and improve retrievability. The method can be applied to future campaigns including ICESat-2 and WCOM. Read more
Colluvial deposits as a possible weathering reservoir in uplifting mountains Earth Surface Dynamics DOI 10.5194/esurf-6-217-2018 21 March 2018 The role of mountain uplift and associated silicate weathering in the global climate over geological times is controversial. Previous soil column models suggest that weathering falls at a high denudation rate. We present the results of a 3-D model that couples erosion and weathering, a CO2consumer during mountain uplift. Our model suggests that the weathering of temporarily stocked colluvium may contribute significantly to the mountain weathering outflux at high denudation rates. Read more
Active heat pulse sensing of 3-D-flow fields in streambeds Hydrology and Earth System Sciences DOI 10.5194/hess-22-1917-2018 20 March 2018 This study used a portable 56-sensor, 3-D temperature array with three heat pulse sources to measure the flow direction and magnitude below the water–sediment interface. Breakthrough curves from each of the sensors were analyzed using a heat transport equation. The use of short-duration heat pulses provided a rapid, accurate assessment technique for determining dynamic and multi-directional flow patterns in the hyporheic zone and is a basis for improved understanding of biogeochemical processes. Read more
Decoupling of dissolved organic matter patterns between stream and riparian groundwater in a headwater forested catchment Hydrology and Earth System Sciences DOI 10.5194/hess-22-1897-2018 19 March 2018 Streams are important sources of carbon to the atmosphere, though knowing whether they merely outgas terrestrially derived carbon dioxide or mineralize terrestrial inputs of dissolved organic matter (DOM) is still a big challenge in ecology. Our study highlights that stream DOM is not merely a reflection of riparian groundwater entering the stream and that headwater streams have the capacity to internally produce, transform, and consume DOM. Read more
Ideas and perspectives: hydrothermally driven redistribution and sequestration of early Archaean biomass – the “hydrothermal pump hypothesis” Biogeosciences DOI 10.5194/bg-15-1535-2018 15 March 2018 The origin of organic matter in the oldest rocks on Earth is commonly ambiguous (biotic vs. abiotic). This problem culminates in the case of hydrothermal chert veins that contain abundant organic matter. Here we demonstrate a microbial origin of kerogen embedded in a 3.5 Gyr old hydrothermal chert vein. We explain this finding with the large-scale redistribution of biomass by hydrothermal fluids, emphasizing the interplay between biological and abiological processes on the early Earth. Read more
A systemic approach for modeling soil functions SOIL DOI 10.5194/soil-4-83-2018 15 March 2018 This paper deals with the importance of soil for our terrestrial environment and the need to predict the impact of soil management on the multitude of functions that soil provides. We suggest to consider soil as a self-organized complex system and provide a concept of how this could be achieved. This includes how soil research, currently fragmented into a number of more or less disjunct disciplines, may be integrated to substantially contribute to a science-based evaluation of soil functions. Read more
Thermodynamics of saline and fresh water mixing in estuaries Earth System Dynamics DOI 10.5194/esd-9-241-2018 13 March 2018 This paper presents a new equation for the dispersion of salinity in alluvial estuaries based on the maximum power concept. The new equation is physically based and replaces previous empirical equations. It is very useful for application in practice because in contrast to previous methods it no longer requires a calibration parameter, turning the method into a predictive method. The paper presents successful applications in more than 23 estuaries in different parts of the world. Read more
Evaluation of stratospheric age of air from CF4, C2F6, C3F8, CHF3, HFC-125, HFC-227ea and SF6; implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials Atmospheric Chemistry and Physics DOI 10.5194/acp-18-3369-2018 8 March 2018 Chemical species measured in stratospheric air can be used as proxies for stratospheric circulation changes which cannot be measured directly. A range of tracers is important to understand changing stratospheric dynamics. We demonstrate the suitability of PFCs and HFCs as tracers and support recent work that reduces the current stratospheric lifetime of SF6. Updates to policy-relevant parameters (e.g. stratospheric lifetime) linked to this change are provided for O3-depleting substances. Read more
From engineering hydrology to Earth system science: milestones in the transformation of hydrologic science Hydrology and Earth System Sciences DOI 10.5194/hess-22-1665-2018 7 March 2018 The paper presents major milestones in the transformation of hydrologic science over the last 50 years from engineering hydrology to Earth system science. This transformation has involved a transition from a focus on time (empirical) to space (Newtonian mechanics), and to time (Darwinian co-evolution). Hydrology is now well positioned to again return to a focus on space or space–time and a move towards regional process hydrology. Read more
Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements Atmospheric Measurement Techniques DOI 10.5194/amt-11-1333-2018 6 March 2018 Tropical atmospheric variability is often described using proxy indices of the Quasi-Biennial Oscillation and the El Niño–Southern Oscillation. We introduce new proxies derived from GNSS radio occultation (RO) satellite measurements. Using the high vertical resolution of the RO temperature fields we obtain altitude-resolved indices which can improve the description of atmospheric variability patterns and can be used in climate studies where a detailed knowledge of these patterns is required. Read more
Results from the Fourth WMO Filter Radiometer Comparison for aerosol optical depth measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-18-3185-2018 6 March 2018 Aerosol optical depth measured from ground-based sun photometers is the most important parameter for studying the changes in the Earth’s radiation balance due to aerosols. Representatives for various sun photometer types belonging to individual institutions or international aerosol networks gather every 5 years, for 3 weeks, in Davos, Switzerland, in order to compare their aeorosol optical depth retrievals. This work presents the results of the latest (fourth) filter radiometer intercomparison. Read more
U–Th and 10Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia Earth Surface Dynamics DOI 10.5194/esurf-6-121-2018 5 March 2018 Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey. Read more
Using hydraulic head, chloride and electrical conductivity data to distinguish between mountain-front and mountain-block recharge to basin aquifers Hydrology and Earth System Sciences DOI 10.5194/hess-22-1629-2018 2 March 2018 This article tackles the problem of finding the origin of groundwater in basin aquifers adjacent to mountains. In particular, we aim to determine whether the recharge occurs predominantly through stream infiltration along the mountain front or through subsurface flow from the mountain. To this end, we discuss the use of routinely measured variables: hydraulic head, chloride and electrical conductivity. A case study from Australia demonstrates the approach. Read more
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. 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