Development of a large-sample watershed-scale hydrometeorological data set for the contiguous USA: data set characteristics and assessment of regional variability in hydrologic model performance Hydrology and Earth System Sciences DOI 10.5194/hess-19-209-2015 14 January 2015 The focus of this paper is to (1) present a community dataset of daily forcing and hydrologic response data for 671 unimpaired basins across the contiguous United States that spans a very wide range of hydroclimatic conditions; and (2) provide a calibrated model performance benchmark using a common conceptual snow and hydrologic modeling system. This benchmark provides a reference level of model performance across a very large basin sample and highlights regional variations in performance. Read more
Seasonal in situ observations of glyoxal and methylglyoxal over the temperate oceans of the Southern Hemisphere Atmospheric Chemistry and Physics DOI 10.5194/acp-15-223-2015 12 January 2015 Glyoxal and methylglyoxal are short-lived organic trace gases and important precursors of secondary organic aerosol. Measurements over oceans are sparse. We present the first in situ glyoxal and methylglyoxal observations over remote temperate oceans, alongside observations of precursor gases. Precursor gases cannot explain observed mixing ratios, highlighting an unknown source. We show a large discrepancy between calculated vertical column densities of glyoxal and those retrieved by satellite. Read more
Internally and externally induced deformations of the magnetospheric equatorial current as inferred from spacecraft data Annales Geophysicae DOI 10.5194/angeo-33-1-2015 6 January 2015 A new quantitative model of the global shape of the neutral sheet in the Earth’s magnetosphere is developed, parameterized by the dipole tilt, solar wind pressure, and IMF By and Bz. The model is based on data from the Polar, Cluster, Geotail, and Themis satellites taken in 1995-2013. The paper quantifies and further explains our earlier finding of the bowl-shaped deformation of the neutral sheet due to the Earth’s dipole tilt (Tsyganenko and Andreeva, GRL, v.41(4), 2014). Read more
Soil properties and pre-Columbian settlement patterns in the Monumental Mounds Region of the Llanos de Moxos, Bolivian Amazon SOIL DOI 10.5194/soil-1-65-2015 6 January 2015 In the present paper we explore to what degree soil properties might have influenced pre-Columbian settlement patterns in the Monumental Mounds Region (MMR) of the Llanos de Moxos (LM), Bolivian Amazon. This study provides new data on the soil properties of the south-eastern Bolivian Amazon and reinforces the hypothesis that environmental constraints and opportunities exerted an important role on pre-Columbian occupation patterns and the population density reached in the Bolivian Amazon. Read more
What causes cooling water temperature gradients in a forested stream reach? Hydrology and Earth System Sciences DOI 10.5194/hess-18-5361-2014 20 December 2014 This study demonstrates the processes by which instantaneous longitudinal water temperature gradients may be generated in a stream reach that transitions from moorland to semi-natural forest in the absence of substantial groundwater inflows. Water did not cool as it flowed downstream. Instead, temperature gradients were generated by a combination of reduced rates of heating in the forested reach and advection of cooler (overnight and early morning) water from the upstream moorland catchment. Read more
Processes determining the marine alkalinity and calcium carbonate saturation state distributions Biogeosciences DOI 10.5194/bg-11-7349-2014 19 December 2014 We examine and discuss the portion of ocean alkalinity that varies in response to carbonate cycling and riverine alkalinity inputs using a new tracer, Alk*. We use this tracer to quantify the controls on marine carbonate saturation: At depth, we find carbonate cycling to be a minor control relative to organic matter cycling and pressure changes. In well-equilibrated surface water, we find carbonate cycling to be less important than temperature changes and freshwater cycling. Read more
Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia Hydrology and Earth System Sciences DOI 10.5194/hess-18-5303-2014 18 December 2014 Hydrological modeling and assessment tools were used to provide evidence of the expected hydrological alterations that hydropower development in the lower Mekong tributaries could bring to the Tonle Sap. The most significant alterations are in terms of water levels during the dry season and rates of water level rise/drop which are crucial for tree seed germination and fish migrations, and therefore major ecological disruptions are likely to follow. Read more
Estimating the volume of glaciers in the Himalayan–Karakoram region using different methods The Cryosphere DOI 10.5194/tc-8-2313-2014 12 December 2014 Existing methods (area-volume relations, a slope-dependent volume estimation method, and two ice-thickness distribution models) are used to estimate the ice reserves stored in Himalayan-Karakoram glaciers. Resulting volumes range from 2955–4737 km³. Results from the ice-thickness distribution models agree well with local measurements; volume estimates from area-related relations exceed the estimates from the other approaches. Evidence on the effect of the selected method on results is provided. Read more
A virtual water network of the Roman world Hydrology and Earth System Sciences DOI 10.5194/hess-18-5025-2014 11 December 2014 Our virtual water network of the Roman World shows that virtual water trade and irrigation provided the Romans with resilience to interannual climate variability. Virtual water trade enabled the Romans to meet food demands from regions with a surplus. Irrigation provided stable water supplies for agriculture, particularly in large river catchments. However, virtual water trade also stimulated urbanization and population growth, which eroded Roman resilience to climate variability over time. Read more
Solar irradiances measured using SPN1 radiometers: uncertainties and clues for development Atmospheric Measurement Techniques DOI 10.5194/amt-7-4267-2014 8 December 2014 This work presents a comprehensive study of SPN1 radiometers accuracy and sources of uncertainty, drawing on laboratory experiments, numerical modelling and comparison studies between measurements from this sensor and state-of-the art instruments for six diverse sites. Several clues are provided for improving the SPN1 accuracy and agreement with state-of-the art measurements. Read more
