bluuebunny/crossref_metadata_2025_split huggingface dataset:
Varying styles of magmatic strain accommodation across the East African Rift
Authors: Muirhead James D. , Kattenhorn Simon A. , Le Corvec Nicolas 
Published: July 2015

AbstractObservations of active dike intrusions provide present day snapshots of the magmatic contribution to continental rifting. However, unravelling the contributions of upper crustal dikes over the timescale of continental rift evolution is a significant challenge. To address this issue, we analyzed the morphologies and alignments of >1500 volcanic cones to infer the distribution and trends of upper crustal dikes in various rift basins across the East African Rift (EAR). Cone lineament data reveal along‐axis variations in the distribution and geometries of dike intrusions as a result of changing tectonomagmatic conditions. In younger (<10 Ma) basins of the North Tanzanian Divergence, dikes are largely restricted to zones of rift‐oblique faulting between major rift segments, referred to here as transfer zones. Cone lineament trends are highly variable, resulting from the interplay between (1) the regional stress field, (2) local magma‐induced stress fields, and (3) stress rotations related to mechanical interactions between rift segments. We find similar cone lineament trends in transfer zones in the western branch of the EAR, such as the Virunga Province, Democratic Republic of the Congo. The distributions and orientations of upper crustal dikes in the eastern branch of the EAR vary during continental rift evolution. In early‐stage rifts (<10 Ma), upper crustal dikes play a limited role in accommodating extension, as they are confined to areas in and around transfer zones. In evolved rift basins (>10 Ma) in Ethiopia and the Kenya Rift, rift‐parallel dikes accommodate upper crustal extension along the full length of the basin.
River geochemistry, chemical weathering, and atmospheric CO2 consumption rates in the Virunga Volcanic Province (East Africa)
Authors: Balagizi Charles M. , Darchambeau François , Bouillon Steven , Yalire Mathieu M. , Lambert Thibault , Borges Alberto V. 
Published: July 2015

AbstractWe report a water chemistry data set from 13 rivers of the Virunga Volcanic Province (VVP) (Democratic Republic of Congo), sampled between December 2010 and February 2013. Most parameters showed no pronounced seasonal variation, whereas their spatial variation suggests a strong control by lithology, soil type, slope, and vegetation. High total suspended matter (289–1467 mg L−1) was recorded in rivers in the Lake Kivu catchment, indicating high soil erodibility, partly as a consequence of deforestation and farming activities. Dissolved and particulate organic carbon (DOC and POC) were lower in rivers from lava fields, and higher in nonvolcanic subcatchments. Stable carbon isotope signatures (δ13C) of POC and DOC mean δ13C of −22.5‰ and −23.5‰, respectively, are the first data to be reported for the highland of the Congo River basin and showed a much higher C4 contribution than in lowland areas. Rivers of the VVP were net sources of CH4 to the atmosphere (4–5052 nmol L−1). Most rivers show N2O concentrations close to equilibrium, but some rivers showed high N2O concentrations related to denitrification in groundwaters. δ13C signatures of dissolved inorganic carbon suggested magmatic CO2 inputs to aquifers/soil, which could have contributed to increase basalt weathering rates. This magmatic CO2‐mediated basalt weathering strongly contributed to the high major cation concentrations and total alkalinity. Thus, chemical weathering (39.0–2779.9 t km−2 yr−1) and atmospheric CO2 consumption (0.4–37.0 × 106 mol km−2 yr−1) rates were higher than previously reported in the literature for basaltic terrains.
Integrated seismic source model of the 2015 Gorkha, Nepal, earthquake
Authors: Yagi Yuji , Okuwaki Ryo 
Published: July 2015

AbstractWe compared spatiotemporal slip‐rate and high‐frequency (around 1 Hz) radiation distributions from teleseismic P wave data to infer the seismic rupture process of the 2015 Gorkha, Nepal, earthquake. For these estimates, we applied a novel waveform inversion formulation that mitigates the effect of Green's functions uncertainty and a hybrid backprojection method that mitigates contamination by depth phases. Our model showed that the dynamic rupture front propagated eastward from the hypocenter at 3.0 km/s and triggered a large‐slip event centered about 50 km to the east. It also showed that the large‐slip event included a rapid rupture acceleration event and an irregular deceleration of rupture propagation before the rupture termination. Heterogeneity of the stress drop or fracture energy in the eastern part of the rupture area, where aftershock activity was high, inhibited rupture growth. High‐frequency radiation sources tended to be in the deeper part of the large‐slip area, which suggests that heterogeneity of the stress drop or fracture energy there may have contributed to the damage in and around Kathmandu.
Effects of subgrid‐scale snow thickness variability on radiative transfer in sea ice
Authors: Abraham Carsten , Steiner Nadja , Monahan Adam , Michel Christine 
Published: July 2015

AbstractSnow is a principal factor in controlling heat and light fluxes through sea ice. With the goal of improving radiative and heat flux estimates through sea ice in regional and global models without the need of detailed snow property descriptions, a new parameterization including subgrid‐scale snow thickness variability is presented. One‐parameter snow thickness distributions depending only on the gridbox‐mean snow thickness are introduced resulting in analytical solutions for the fluxes of heat and light through the snow layer. As the snowpack melts, these snow thickness distributions ensure a smooth seasonal transition of the light field under sea ice. Spatially homogenous melting applied to an inhomogeneous distribution of snow thicknesses allows the appearance of bare sea ice areas and melt ponds before all snow has melted. In comparison to uniform‐thickness snow used in previous models, the bias in the under sea‐ice light field is halved with this parameterization. Model results from a one‐dimensional ocean turbulence model coupled with a thermodynamic sea ice model are compared to observations near Resolute in the Canadian High Arctic. The simulations show substantial improvements not only to the light field at the sea ice base which will affect ice algal growth but also to the sea ice and seasonal snowpack evolution. During melting periods, the snowpack can survive longer while sea ice thickness starts to reduce earlier.
Variability of Labrador Sea Water transported through Flemish Pass during 1993–2013
Authors: Schneider Linn , Kieke Dagmar , Jochumsen Kerstin , Colbourne Eugene , Yashayaev Igor , Steinfeldt Reiner , Varotsou Eirini , Serra Nuno , Rhein Monika 
Published: July 2015

AbstractFlemish Pass, located at the western subpolar margin, is a passage (sill depth 1200 m) that is constrained by the Grand Banks and the underwater plateau Flemish Cap. In addition to the Deep Western Boundary Current (DWBC) pathway offshore of Flemish Cap, Flemish Pass represents another southward transport pathway for two modes of Labrador Sea Water (LSW), the lightest component of North Atlantic Deep Water carried with the DWBC. This pathway avoids potential stirring regions east of Flemish Cap and deflection into the interior North Atlantic. Ship‐based velocity measurements between 2009 and 2013 at 47°N in Flemish Pass and in the DWBC east of Flemish Cap revealed a considerable southward transport of Upper LSW through Flemish Pass (15–27%, −1.0 to −1.5 Sv). About 98% of the denser Deep LSW were carried around Flemish Cap as Flemish Pass is too shallow for considerable transport of Deep LSW. Hydrographic time series from ship‐based measurements show a significant warming of 0.3°C/decade and a salinification of 0.03/decade of the Upper LSW in Flemish Pass between 1993 and 2013. Almost identical trends were found for the evolution in the Labrador Sea and in the DWBC east of Flemish Cap. This indicates that the long‐term hydrographic variability of Upper LSW in Flemish Pass as well as in the DWBC at 47°N is dominated by changes in the Labrador Sea, which are advected southward. Fifty years of numerical ocean model simulations in Flemish Pass suggest that these trends are part of a multidecadal cycle.
Evaluation of MODIS aerosol retrieval algorithms over the Beijing‐Tianjin‐Hebei region during low to very high pollution events
Authors: Bilal Muhammad , Nichol Janet E. 
Published: July 2015

AbstractThis study evaluates the performance of different MODerate resolution Imaging Spectroradiometer (MODIS) aerosol algorithms during fine particle pollution events over the Beijing‐Tianjin‐Hebei region using Aerosol Robotic Network aerosol optical depth (AOD). These algorithms include the Deep Blue (DB) Collection 5.1 (C5) and Collection 6 (C6) algorithms at 10 km resolution, the Dark Target (DT) C5 and C6 algorithms at 10 km, the DT C6 algorithm at 3 km, and the Simplified Aerosol Retrieval Algorithm (SARA) at 500 m, 3 km, and 10 km resolutions. The DB C6 retrievals have 34–39% less uncertainties, 2–3 times smaller root‐mean‐square error (RMSE), and 3–4 times smaller mean absolute error (MAE) than DB C5 retrievals. The DT C6 has 4–8% lower bias, 4–12% less overestimation, and smaller RMSE and MAE errors than DT C5. Due to underestimation of surface reflectance and the use of inappropriate aerosol schemes, 87–89% of the collocations of the DT C6 at 3 km fall above the expected error (EE), with overestimation of 64–79% which is 15–27% higher than that for the DT C6 at 10 km. The results suggest that the DT C6 at 3 km resolution is less reliable than that at 10 km. The SARA AOD has small RMSE and MAE errors with 90–96% of the collocations falling within the EE. Overall, the SARA showed 15–16% less uncertainty than the DB C6 (10 km), 69–72% less than the DT C6 (10 km), and 79–83% less than the DT C6 (3 km) retrievals.
A hybrid framework for assessing socioeconomic drought: Linking climate variability, local resilience, and demand
Authors: Mehran Ali , Mazdiyasni Omid , AghaKouchak Amir 
Published: July 2015

AbstractSocioeconomic drought broadly refers to conditions whereby the water supply cannot satisfy the demand. Most previous studies describe droughts based on large‐scale meteorological/hydrologic conditions, ignoring the demand and local resilience to cope with climate variability. Reservoirs provide resilience against climatic extremes and play a key role in water supply and demand management. Here we outline a unique multivariate approach as a measure of socioeconomic drought, termed Multivariate Standardized Reliability and Resilience Index (MSRRI). The model combines information on the inflow and reservoir storage relative to the demand. MSRRI combines (I) a “top‐down” approach that focuses on processes/phenomena that cannot be simply controlled or altered by decision makers, such as climate change and variability, and (II) a “bottom‐up” methodology that represents the local resilience and societal capacity to respond or adapt to droughts. MSRRI is based on a nonparametric multivariate distribution function that links inflow‐demand reliability indicator to water storage resilience indicator. These indicators are used to assess socioeconomic drought during the Australian Millennium drought (1998–2010) and the 2011–2014 California drought. The results show that MSRRI is superior to univariate indices because it captures both early onset and persistence of water stress over time. The suggested framework can be applied to both individual reservoirs and a group of reservoirs in a region, and it is consistent with the currently available standardized drought indicators. MSRRI provides complementary information on socioeconomic drought development and recovery based on reservoir storage and demand that cannot be achieved from the commonly used drought indicators.
What controls the seasonal cycle of black carbon aerosols in India?
Authors: Kumar Rajesh , Barth M. C. , Pfister G. G. , Nair V. S. , Ghude Sachin D. , Ojha N. 
Published: July 2015

AbstractThe seasonal variability of black carbon (BC) aerosols in India is studied using high resolution (10 km) BC simulations conducted using the Weather Research and Forecasting Model coupled with Chemistry. The model reproduces the observed seasonality of surface BC fairly well over most parts of India but fails to capture the seasonality in the Himalayas and deviates from the observed BC magnitude at several sites. The errors in modeled BC are attributed to uncertainties in BC emissions and their diurnal cycle, planetary boundary layer height underestimation, and aerosol processes. Model results show distinct but opposite seasonality of BC in the lower (LT) and free troposphere (FT) with BC showing winter maximum and summer minimum in the LT and vice versa in the FT. Our analysis shows that BC seasonality is not driven by seasonality of the anthropogenic emissions but by changes in the regional meteorology through weakening of the horizontal transport and strengthening of the vertical transport of BC during summertime compared to winter. BC in both the LT and FT comes mostly from anthropogenic emissions followed by biomass burning emissions except during winter when long‐distant sources become more important in the FT. BC in the FT is significantly affected by anthropogenic emissions from all parts of India. The source‐receptor relationship changes seasonally, but the regional transport remains a significant contributor to BC loadings in the LT of India, highlighting the necessity of considering nonlocal sources along with local emissions when designing strategies for mitigating BC impacts on air quality.
Separating aerosol microphysical effects and satellite measurement artifacts of the relationships between warm rain onset height and aerosol optical depth
Authors: Zhu Yannian , Rosenfeld Daniel , Yu Xing , Li Zhanqing 
Published: July 2015

AbstractThe high resolution (375 m) of the Visible Infrared Imaging Radiometer Suite on board the Suomi National Polar‐Orbiting Partnership satellite allows retrieving relatively accurately the vertical evolution of convective cloud drop effective radius (re) with height or temperature. A tight relationship is found over SE Asia and the adjacent seas during summer between the cloud‐free aerosol optical depth (AOD) and the cloud thickness required for the initiation of warm rain, as represented by the satellite‐retrieved cloud droplet re of 14 µm, for a subset of conditions that minimize measurement artifacts. This cloud depth (ΔT14) is parameterized as the difference between the cloud base temperature and the temperature at the height where re exceeds 14 µm (T14). For a unit increase of AOD, the height of rain initiation is increased by about 5.5 km. The concern of data artifacts due to the increase in AOD near clouds was mitigated by selecting only scenes with cloud fraction (CF) < 0.1. For CF > 0.1 and ΔT14 > ~20°C, the increase of ΔT14 gradually levels off with further increase of AOD, possibly because the AOD is enhanced by aerosol upward transport and detrainment through the clouds below the T14 isotherm. The bias in the retrieved re due to the different geometries of solar illumination was also quantified. It was shown that the retrievals are valid only for backscatter views or when avoiding scenes with significant amount of cloud self‐shadowing. These artifacts might have contributed to past reported relationships between cloud properties and AOD.
Methane release from pingo‐like features across the South Kara Sea shelf, an area of thawing offshore permafrost
Authors: Serov Pavel , Portnov Alexey , Mienert Jurgen , Semenov Peter , Ilatovskaya Polina 
Published: July 2015

AbstractThe Holocene marine transgression starting at ~19 ka flooded the Arctic shelves driving extensive thawing of terrestrial permafrost. It thereby promoted methanogenesis within sediments, the dissociation of gas hydrates, and the release of formerly trapped gas, with the accumulation in pressure of released methane eventually triggering blowouts through weakened zones in the overlying and thinned permafrost. Here we present a range of geophysical and chemical scenarios for the formation of pingo‐like formations (PLFs) leading to potential blowouts. Specifically, we report on methane anomalies from the South Kara Sea shelf focusing on two PLFs imaged from high‐resolution seismic records. A variety of geochemical methods are applied to study concentrations and types of gas, its character, and genesis. PLF 1 demonstrates ubiquitously low‐methane concentrations (14.2–55.3 ppm) that are likely due to partly unfrozen sediments with an ice‐saturated internal core reaching close to the seafloor. In contrast, PLF 2 reveals anomalously high‐methane concentrations of >120,000 ppm where frozen sediments are completely absent. The methane in all recovered samples is of microbial and not of thermogenic origin from deep hydrocarbon sources. However, the relatively low organic matter content (0.52–1.69%) of seafloor sediments restricts extensive in situ methane production. As a consequence, we hypothesize that the high‐methane concentrations at PLF 2 are due to microbial methane production and migration from a deeper source.
Geological and meteorological controls on icing (aufeis) dynamics (1985 to 2014) in subarctic Canada
Authors: Morse P. D. , Wolfe S. A. 
Published: July 2015

AbstractIcings are widespread yet poorly understood winter hydrological phenomena that develop over the winter by freezing successive overflows of groundwater to the surface. Groundwater hydrology in arctic regions is constrained by geological setting and permafrost extent, and overflows are possibly driven by cold winters, winter warming intervals, high antecedent autumn rainfall, and low early winter snowfall. Consequently, icings are spatially recurrent but not necessarily annually nor to the same extent. We test the significance of identified meteorological forcing variables against a long‐term data set of icing dynamics and distribution we developed for the Great Slave region around Yellowknife, Northwest Territories. Climate is regionally consistent, but variable geology and permafrost create hydrological conditions representative of much of the subarctic. We mapped 5500 icings in the study area (21,887 km2) with a semiautomated approach utilizing late spring Landsat archival images (1985 to 2014). Individual icing size, ranging 3 orders of magnitude (1.8 × 10−3 km2 to 4.1 km2), is related to return frequency. Infrequent ice (25% return frequency) accounts for 94% of the total icing area (86 km2). Winter warming intervals (≥5°C; typically over 1–3 days) and autumn rainfall (September and October) explain 28% of icing density interannual variation overall. Interannual icing variation and significant meteorological forcing variables differ among ecoregions where varied geological settings and permafrost conditions influence the hydrological regime. Future icings may develop less frequently due to decreasing winter warming intervals, but increasing autumn rainfall may increase icing density where Canadian Shield leads to strong threshold‐mediated runoff generation processes.
Particulate nitrogen exports in stream runoff exceed dissolved nitrogen forms during large tropical storms in a temperate, headwater, forested watershed
Authors: Inamdar Shreeram , Dhillon Gurbir , Singh Shatrughan , Parr Thomas , Qin Zhixuan 
Published: July 2015

AbstractAlthough lasting only a fraction of the year, large storms may represent a significant, but highly variable, control on watershed nitrogen (N) fluxes. We determined the exports of particulate N (PN) and total dissolved N including nitrate‐N (NO3‐N) and dissolved organic N (DON) in streamflow from a 12 ha temperate forested watershed. Sampling was performed for 15 storms over September 2010 to December 2012 and included four large tropical storms—Nicole (2010), Irene and Lee (2011), and Sandy (2012). PN composed a substantial portion (39–87%) of the storm event N export with storms constituting 65% of the 2011 PN export. Tropical storm Irene alone generated 1.76 kg N ha−1 of PN which was 27% of the annual watershed N (6.43 kg N ha−1) export for 2011. In contrast, tropical storm Sandy (October 2012) yielded low sediment and PN exports, likely due to low precipitation intensity and a freshly fallen leaf cover that may have reduced soil erosion. Stream water concentrations of PN, NO3‐N, and DON ranged from 0–17.5, 0–2.02, and 0.01–0.54 mg N L−1, respectively. Nitrate‐N concentrations displayed a dilution trajectory for peak stormflows suggesting supply limitation, a response that was not as strong for PN. These results underscore the importance of large storms for PN export which is significant given that climate‐change predictions indicate an increasing intensity of large tropical storms for the northeast U.S.. Elevated PN exports could further exacerbate water quality and eutrophication problems in sensitive aquatic ecosystems already subjected to excess dissolved nitrogen loads.
A hierarchical bayesian analysis of parasite prevalence and sociocultural outcomes: The role of structural racism and sanitation infrastructure
Authors: Ross Cody T. , Winterhalder Bruce 
Published: July 2015

ObjectivesWe conduct a revaluation of the Thornhill and Fincher research project on parasites using finely‐resolved geographic data on parasite prevalence, individual‐level sociocultural data, and multilevel Bayesian modeling. In contrast to the evolutionary psychological mechanisms linking parasites to human behavior and cultural characteristics proposed by Thornhill and Fincher, we offer an alternative hypothesis that structural racism and differential access to sanitation systems drive both variation in parasite prevalence and differential behaviors and cultural characteristics.MethodsWe adopt a Bayesian framework to estimate parasite prevalence rates in 51 districts in eight Latin American countries using the disease status of 170,220 individuals tested for infection with the intestinal roundworm Ascaris lumbricoides (Hürlimann et al., []: PLoS Negl Trop Dis 5:e1404). We then use district‐level estimates of parasite prevalence and individual‐level social data from 5,558 individuals in the same 51 districts (Latinobarómetro, 2008) to assess claims of causal associations between parasite prevalence and sociocultural characteristics.ResultsWe find, contrary to Thornhill and Fincher, that parasite prevalence is positively associated with preferences for democracy, negatively associated with preferences for collectivism, and not associated with violent crime rates or gender inequality. A positive association between parasite prevalence and religiosity, as in Fincher and Thornhill (: Behav Brain Sci 35:61–79), and a negative association between parasite prevalence and achieved education, as predicted by Eppig et al. (: Proc R S B: Biol Sci 277:3801–3808), become negative and unreliable when reasonable controls are included in the model. We find support for all predictions derived from our hypothesis linking structural racism to both parasite prevalence and cultural outcomes.ConclusionsWe conclude that best practices in biocultural modeling require examining more than one hypothesis, retaining individual‐level data and its associated variance whenever possible, and adopting multilevel techniques suited to the structuring of the data. Am. J. Hum. Biol. 28:74–89, 2016. © 2015 Wiley Periodicals, Inc.