Trends in global tropospheric ozone inferred from a composite record of TOMS/OMI/MLS/OMPS satellite measurements and the MERRA-2 GMI simulation Atmospheric Chemistry and Physics DOI 10.5194/acp-19-3257-2019 13 March 2019 Both a 38-year merged satellite record of tropospheric ozone from TOMS/OMI/MLS/OMPS and a MERRA-2 GMI model simulation show large increases of 6–7 Dobson units from the Near East to India–East Asia and eastward over the Pacific. These increases in tropospheric ozone are attributed to increases in pollution over the region over the last several decades. Secondary 38-year increases of 4–5 Dobson units with both GMI model and satellite measurements occur over central African–tropical Atlantic. Read more
Attributing the 2017 Bangladesh floods from meteorological and hydrological perspectives Hydrology and Earth System Sciences DOI 10.5194/hess-23-1409-2019 13 March 2019 In August 2017 Bangladesh faced one of its worst river flooding events in recent history. For the large Brahmaputra basin, using precipitation alone as a proxy for flooding might not be appropriate. In this paper we explicitly test this assumption by performing an attribution of both precipitation and discharge as a flooding-related measure to climate change. We find the change in risk to be of similar order of magnitude (between 1 and 2) for both the meteorological and hydrological approach. Read more
Effects of univariate and multivariate bias correction on hydrological impact projections in alpine catchments Hydrology and Earth System Sciences DOI 10.5194/hess-23-1339-2019 11 March 2019 Several multivariate bias correction methods have been developed recently, but only a few studies have tested the effect of multivariate bias correction on hydrological impact projections. This study shows that incorporating or ignoring inter-variable relations between air temperature and precipitation can have a notable effect on the projected snowfall fraction. The effect translated to considerable consequences for the glacio-hydrological responses and streamflow components of the catchments. Read more
Late Miocene–Pliocene climate evolution recorded by the red clay cover on the Xiaoshuizi planation surface, NE Tibetan Plateau Climate of the Past DOI 10.5194/cp-15-405-2019 11 March 2019 Multiple proxies for the XSZ planation surface reveal that the climate was dry and stable during the late Miocene but became intermittently humid with more seasonality at 4.7–3.9 Ma. Regional climatic differences between the central and western CLP reveal that expansion of the paleo-EASM occurred during the early Pliocene. The warming of the high northern latitudes in response to the closure of the Panama Seaway may have been responsible for the thermodynamical enhancement of the paleo–EASM. Read more
The Open Global Glacier Model (OGGM) v1.1 Geoscientific Model Development DOI 10.5194/gmd-12-909-2019 8 March 2019 Mountain glaciers are one of the few remaining subsystems of the global climate system for which no globally applicable community-driven model exists. Here we present the Open Global Glacier Model (OGGM; www.oggm.org), developed to provide a modular and open-source numerical model framework for simulating past and future change of any glacier in the world. Read more
Conservative finite-volume forms of the Saint-Venant equations for hydrology and urban drainage Hydrology and Earth System Sciences DOI 10.5194/hess-23-1281-2019 7 March 2019 A new derivation of the equations for one-dimensional open-channel flow in rivers and storm drainage systems has been developed. The new approach solves some long-standing problems for obtaining well-behaved solutions with conservation forms of the equations. This research was motivated by the need for highly accurate models of large-scale river networks and the storm drainage systems in megacities. Such models are difficult to create with existing equation forms. Read more
Seasonal origins of soil water used by trees Hydrology and Earth System Sciences DOI 10.5194/hess-23-1199-2019 1 March 2019 We used stable isotopes of xylem water to study differences in the seasonal origin of water in more than 900 individual trees from three dominant species in 182 Swiss forested sites. We discovered that midsummer transpiration was mostly supplied by winter precipitation across diverse humid climates. Our findings provide new insights into tree vulnerability to droughts, transport of water (and thus solutes) in soils, and the climatic information conveyed by plant-tissue isotopes. Read more
The Reference Elevation Model of Antarctica The Cryosphere DOI 10.5194/tc-13-665-2019 26 February 2019 The Reference Elevation Model of Antarctica (REMA) is the first continental-scale terrain map at less than 10 m resolution, and the first with a time stamp, enabling measurements of elevation change. REMA is constructed from over 300 000 individual stereoscopic elevation models (DEMs) extracted from submeter-resolution satellite imagery. REMA is vertically registered to satellite altimetry, resulting in errors of less than 1 m over most of its area and relative uncertainties of decimeters. Read more
Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: methods of calculation, applications, and confidence limits Atmospheric Measurement Techniques DOI 10.5194/amt-12-1219-2019 26 February 2019 The abundance of freezing nuclei in water samples is routinely determined by experiments involving the cooling of sample drops and observing the temperatures at which the drops freeze. This is used for characterizing the nucleating abilities of materials in laboratory preparations or to determine the numbers of nucleating particles in rain, snow, river water or other natural waters. The evaluation of drop-freezing experiments in terms of differential nucleus spectra is advocated in the paper. Read more
The role of moisture transport for precipitation in the inter-annual and inter-daily fluctuations of the Arctic sea ice extension Earth System Dynamics DOI 10.5194/esd-10-121-2019 21 February 2019 Ice melting at the scale of inter-annual fluctuations against the trend is favoured by an increase in moisture transport in summer, autumn, and winter and a decrease in spring. On a daily basis extreme humidity transport increases the formation of ice in winter and decreases it in spring, summer, and autumn; in these three seasons it thus contributes to Arctic sea ice melting. These patterns differ sharply from that linked to decline, especially in summer when the opposite trend applies. Read more