bluuebunny/crossref_metadata_2025_split huggingface dataset:
An OGCM study of the impact of rain and river water forcing on the Bay of Bengal
Authors: Behara Ambica , Vinayachandran P. N. 
Published: March 2016

AbstractIndividual and combined effects of rainfall and river discharge on the Bay of Bengal (BoB) is investigated using an Ocean General Circulation Model. A set of four sensitivity experiments, forced with same air‐sea heat flux, but retaining either river runoff or rainfall or both is carried out. These experiments show that the river water is exported out of the bay along the western boundary during winter and rain water along the eastern boundary during summer. Runoff leads to a large (>3 psu) decrease in salinity in the northern bay during summer and along the western boundary during winter, with a weaker contribution from rainfall. The sea surface temperature response to freshwater forcing shows large spatial variations with eastern bay showing higher differences. The northwestern bay warms by ∼1.5°C in the presence of freshwater during summer, due to greater heat absorption within a shallow mixed layer (ML). This warming is caused in nearly equal proportions by rain and river water in early summer, but the contribution by river water dominates during peak and withdrawal phases of the summer monsoon. Northeastern bay, in contrast, is cooler by 1.5–3°C in the presence of freshwater, caused primarily by river runoff, owing to the winter cooling over a thin ML. Temperature inversions form due to surface cooling of a river stratified layer during winter in the northwestern bay and due to radiation penetrating below the ML during summer in the northeastern bay.
A high resolution salinity time series 1993–2012 in the North Atlantic from Argo and Altimeter data
Authors: Stendardo I. , Rhein M. , Hollmann R. 
Published: March 2016

AbstractThe study of salinity changes has been hampered by the lack of temporal and spatial resolution of the observations. In order to improve the spatial and temporal distribution of salinity observations, we used the Gravest Empirical Mode (GEM) technique to calculate high‐resolution salinity distributions as a function of dynamic height for the period 1993–2012. This technique combined Argo and altimeter data to exploit the relationship between T/S profiles and dynamic height in the North Atlantic. The method was valid in the upper 700 m mainly at and near the pathways of the North Atlantic Current (NAC), but failed in regions with weak stratification or with ambiguities in the T/S relationships. Coherent, multiannual large‐scale variability was observed, with many features present in all regions, albeit with weaker amplitudes in the eastern basins. Some of the interannual features in the northeastern Atlantic basins were unrelated to the variability further south and west, pointing to an occasional advection of subtropical water in the eastern Atlantic. Origin and advection of salinity anomalies with the NAC from the North American Basin into the western subpolar North Atlantic are correlated with the state of the North Atlantic Oscillation (NAO) and dampened by the surface freshwater fluxes. Other mechanisms influencing the salinity pattern are the changing location of the subpolar front, also related to the NAO. The large multiyear variability in the 20 year time series obscured any potential trends caused by global warming. Only the Rockall Trough showed a salinity increase of 0.03 per decade.
Intensification of the subpolar front in the Sea of Japan during winter cyclones
Authors: Zhao Ning , Iwasaki Shinsuke , Isobe Atsuhiko , Lien Ren‐Chieh , Wang Bin 
Published: March 2016

AbstractThe response of the subpolar front in the Sea of Japan (also known as the East Sea) to winter cyclones is investigated based on quantitative analyses of gridded and satellite data sets. Cyclone passages affecting the sea are detected using time series of spatially averaged surface turbulent heat fluxes. As the cyclones develop, there are strong cold‐air outbreaks that produce twice the normal heat loss over the sea. After removal of sea surface temperature (SST) seasonal trends, we found that cyclone passage (hence, cooling) mainly occurred over 3 days, with maximum SST reduction of −0.4°C. The greatest reduction was found along the subpolar front, where frontal sharpness (i.e., SST gradient) increased by 0.1°C (100 km)−1. Results of a mixed‐layer model were consistent with both temperature and frontal sharpness, and localized surface cooling along the subpolar front resulted from both horizontal heat advection and turbulent heat fluxes at the sea surface. Further analyses show that this localized cooling from horizontal heat advection is caused by the cross‐frontal Ekman flow (vertically averaged over the mixed layer) and strong northwesterly winds associated with the cold‐air outbreak during cyclone passage.
Multiple phase screen calculation of two‐way spherical wave propagation in the ionosphere
Authors: Knepp Dennis L. 
Published: March 2016

AbstractThis paper presents a numerical solution to the parabolic wave equation for spherical wave propagation in a disturbed ionosphere. The solution uses the Fourier/split step approach where the propagation medium is modeled using multiple phase‐changing screens separated by free space. The phase screens can consist of deterministic or random components describing spatial scales of any size. This solution consists of realizations of the signal (i.e., the ionospheric transfer function) after two‐way propagation from a transmitter, through the medium to a target, and back. The transmitter and target can be comprised of multiple, independent point scatterers. The solution is applicable to many propagation problems including synthetic aperture radar and is not subject to the small‐scene limitation, where all scatterers in the scene experience identical propagation conditions. Several examples are given illustrating some features of the solution including reciprocity, relationship between one‐ and two‐way (monostatic and bistatic) scintillation index, and reflection from a large target.
Smart pilot points using reversible‐jump Markov‐chain Monte Carlo
Authors: Jiménez S. , Mariethoz G. , Brauchler R. , Bayer P. 
Published: March 2016

AbstractPilot points are typical means for calibration of highly parameterized numerical models. We propose a novel procedure based on estimating not only the pilot point values, but also their number and suitable locations. This is accomplished by a trans‐dimensional Bayesian inversion procedure that also allows for uncertainty quantification. The utilized algorithm, reversible‐jump Markov‐Chain Monte Carlo (RJ‐MCMC), is computationally demanding and this challenges the application for model calibration. We present a solution for fast, approximate simulation through the application of a Bayesian inversion. A fast pathfinding algorithm is used to estimate tracer travel times instead of doing a full transport simulation. This approach extracts the information from measured breakthrough curves, which is crucial for the reconstruction of aquifer heterogeneity. As a result, the “smart pilot points” can be tuned during thousands of rapid model evaluations. This is demonstrated for both a synthetic and a field application. For the selected synthetic layered aquifer, two different hydrofacies are reconstructed. For the field investigation, multiple fluorescent tracers were injected in different well screens in a shallow alluvial aquifer and monitored in a tomographic source‐receiver configuration. With the new inversion procedure, a sand layer was identified and reconstructed with a high spatial resolution in 3‐D. The sand layer was successfully validated through additional slug tests at the site. The promising results encourage further applications in hydrogeological model calibration, especially for cases with simulation of transport.
Robust flood frequency analysis: Performance of EMA with multiple Grubbs‐Beck outlier tests
Authors: Lamontagne J. R. , Stedinger J. R. , Yu Xin , Whealton C. A. , Xu Ziyao 
Published: March 2016

AbstractFlood frequency analysis generally involves the use of simple parametric probability distributions to smooth and extrapolate the information provided by short flood records to estimate extreme flood flow quantiles. Parametric probability distributions can have difficulty simultaneously fitting both the largest and smallest floods. A danger is that the smallest observations in a record can distort the exceedance probabilities assigned to the large floods of interest. The identification and treatment of such Potentially Influential Low Floods (PILFs) frees a fitting algorithm to describe the distribution of the larger observations. This can allow parametric flood frequency analysis to be both efficient, and also robust to deviations from the proposed probability model's lower tail. Historically, PILF identification involved subjective judgement. We propose a new multiple Grubbs‐Beck outlier test (MGBT) for objective PILF identification. MGBT PILF identification rates (akin to Type I errors) are reported for the lognormal (LN) distribution and the log‐Pearson Type III (LP3) distribution with a variety of skew coefficients. MGBT PILF identification generally matched subjective identification from a recent California flood frequency study. Monte Carlo results show that censoring of PILFs identified by the MGBT algorithm improves the extreme quantile estimator efficiency of the expected moments algorithm (EMA) for negatively skewed LP3 distributions and has little effect for zero or positive skews; simultaneously it protects against deviations from the LP3 in the lower tail, as illustrated by distorted LN examples. Thus, MGBT generally makes flood frequency analysis based on the LP3 distribution with EMA both more accurate and more robust.
Simulating bioclogging effects on dynamic riverbed permeability and infiltration
Authors: Newcomer Michelle E. , Hubbard Susan S. , Fleckenstein Jan H. , Maier Ulrich , Schmidt Christian , Thullner Martin , Ulrich Craig , Flipo Nicolas , Rubin Yoram 
Published: March 2016

AbstractBioclogging in rivers can detrimentally impact aquifer recharge. This is particularly so in dry regions, where losing rivers are common, and where disconnection between surface water and groundwater (leading to the development of an unsaturated zone) can occur. Reduction in riverbed permeability due to biomass growth is a time‐variable parameter that is often neglected, yet permeability reduction from bioclogging can introduce order of magnitude changes in seepage fluxes from rivers over short (i.e., monthly) timescales. To address the combined effects of bioclogging and disconnection on infiltration, we developed numerical representations of bioclogging processes within a one‐dimensional, variably saturated flow model representing losing‐connected and losing‐disconnected rivers. We tested these formulations using a synthetic case study informed with biological data obtained from the Russian River, California, USA. Our findings show that modeled biomass growth reduced seepage for losing‐connected and losing‐disconnected rivers. However, for rivers undergoing disconnection, infiltration declines occurred only after the system was fully disconnected. Before full disconnection, biologically induced permeability declines were not significant enough to offset the infiltration gains introduced by disconnection. The two effects combine to lead to a characteristic infiltration curve where peak infiltration magnitude and timing is controlled by permeability declines relative to hydraulic gradient gains. Biomass growth was found to hasten the onset of full disconnection; a condition we term ‘effective disconnection’. Our results show that river infiltration can respond dynamically to bioclogging and subsequent permeability declines that are highly dependent on river connection status.
Fluvial geomorphology and aquatic‐to‐terrestrial Hg export are weakly coupled in small urban streams of Columbus, Ohio
Authors: P. Sullivan S. Mažeika , Boaz Lindsey E. , Hossler Katie 
Published: March 2016

AbstractAlthough mercury (Hg) contamination is common in stream ecosystems, mechanisms governing bioavailability and bioaccumulation in fluvial systems remain poorly resolved as compared to lentic systems. In particular, streams in urbanized catchments are subject to fluvial geomorphic alterations that may contribute to Hg distribution, bioaccumulation, and export across the aquatic‐to‐terrestrial boundary. In 12 streams of urban Columbus, Ohio, we investigated the influence of fluvial geomorphic characteristics related to channel geometry, streamflow, and sediment size and distribution on (1) Hg concentrations in sediment and body burdens in benthic larval and adult emergent aquatic insects and (2) aquatic‐to‐terrestrial contaminant transfer to common riparian spiders of the families Pisauridae and Tetragnathidae via changes in aquatic insect Hg body burdens as well as in aquatic insect density and community composition. Hydrogeomorphic characteristics were weakly related to Hg body burdens in emergent insects (channel geometry) and tetragnathid spiders (streamflow), but not to Hg concentrations in sediment or benthic insects. Streamflow characteristics were also related to emergent insect density, while wider channels were associated with benthic insect community shifts toward smaller‐bodied and more tolerant taxa (e.g., Chironomidae). Thus, our results provide initial evidence that fluvial geomorphology may influence aquatic‐to‐terrestrial contaminant Hg transfer through the collective effects on emergent insect body burdens as well as on aquatic insect community composition and abundance.
Transmission and division of total optical depth method: A universal calibration method for Sun photometric measurements
Authors: Zhang Ming , Gong Wei , Ma Yingying , Wang Lunche , Chen Zhongyong 
Published: March 2016

AbstractSun photometric measurements, which provide accurate and timely information on atmospheric components such as aerosols, clouds, and gases are important to climate research. For regions with heavy and variable aerosol loading, the traditional Langley plot method cannot be applied for Sun photometric instrument calibration, as almost no suitable prolonged periods with stable atmosphere and low‐aerosol loading occurs. An improved calibration method, namely, the transmission and division of total optical depth method, is proposed in this study. Atmospheric total optical depth variation information obtained via other methods is transmitted, and period groups with similar atmospheric extinction effects are selected for Langley regression. This method is validated through calibration of a multifilter rotating shadowband radiometer under heavy aerosol‐loading conditions. The obtained aerosol optical depth (AOD) compares well with the interpolated AOD from a Cimel Sun‐sky radiometer.
The impact of groundwater depletion on spatial variations in sea level change during the past century
Authors: Veit Emeline , Conrad Clinton P. 
Published: March 2016

AbstractContinental groundwater loss during the past century has elevated sea level by up to ~25 mm. The mass unloading associated with this depletion locally uplifts Earth's solid surface and depresses the geoid, leading to slower relative sea level rise near areas of significant groundwater loss. We computed spatial variations in sea level using a model of the solid Earth's response to estimates of groundwater depletion during the past century and find large negative deviations of ~0.4 mm/yr along the coastlines of western North America and southern Asia. This approximately corresponds to the difference between rates of sea level rise measured by tide gauges in these regions since 1930 and average rates inferred from global reconstructions. Groundwater‐induced regional variations in sea level can be larger than those due to postglacial rebound and interseismic deformation and should become increasingly important in the future as both groundwater depletion and sea level rise accelerate.
Multiscale structure of meanders
Authors: Vermeulen B. , Hoitink A. J. F. , Zolezzi G. , Abad J. D. , Aalto R. 
Published: March 2016

AbstractRiver meander planforms can be described based on wavelet analysis, but an objective method to identify the main characteristics of a meander planform over all spatial scales is yet to be found. Here we show how a set of simple metrics representing meander shape can be retrieved from a continuous wavelet transform of a planform geometry. We construct a synoptic multiple looping tree to establish the meander structure, revealing the embedding of dominant meander scales in larger‐scale loops. The method can be applied beyond the case of rivers to unravel the meandering structure of lava flows, turbidity currents, tidal channels, rivulets, supraglacial streams, and extraterrestrial flows.
Joint editorial: Fostering innovation and improving impact assessment for journal publications in hydrology
Authors: Koutsoyiannis Demetris , Blöschl Günter , Bárdossy András , Cudennec Christophe , Hughes Denis , Montanari Alberto , Neuweiler Insa , Savenije Hubert 
Published: March 2016

AbstractEditors of several journals in the field of hydrology met during the Assembly of the International Association of Hydrological Sciences—IAHS (within the Assembly of the International Union of Geodesy and Geophysics—IUGG) in Prague in June 2015. This event was a follow‐up of a similar meeting held in July 2013 in Gothenburg (as reported by Blöschl et al. [2014]). These meetings enable the group of editors to review the current status of the journals and the publication process, and share thoughts on future strategies. Journals were represented in the 2015 meeting through their editors, as shown in the list of authors. The main points on fostering innovation and improving impact assessment in journal publications in hydrology are communicated in this joint editorial published in the above journals.
Appreciation of peer reviewers for 2015
Authors: Montanari Alberto , Bahr Jean , Blöschl Günter , Cai Ximing , Scott Mackay D. , Michalak Anna , Rajaram Harihar , Sanchez‐Vila Xavier 
Published: March 2016

AbstractOn behalf of the journal, AGU, and the scientific community, the editors would like to sincerely thank those who reviewed manuscripts for Water Resources Research in 2015. The hours reading and commenting on manuscripts not only improves the manuscripts themselves but it also increases the scientific rigor of future research in the field. Many of those listed below went beyond and reviewed three or more manuscripts for our journal, and those are indicated in italics. The refereeing contributions they made contributed to 3622 individual reviews of 1434 manuscripts. Thank you again. We look forward to a 2016 of exciting advances in the field and communicating those advances to our community and to the broader public.
Association of Improvement in Pain With Therapeutic Response as Determined by Individual Improvement Criteria in Patients With Rheumatoid Arthritis
Authors: Scharbatke Eva C. , Behrens Frank , Schmalzing Marc , Koehm Michaela , Greger Gerd , Gnann Holger , Burkhardt Harald , Tony Hans‐Peter 
Published: March 2016

ObjectiveTo use statistical methods to establish a threshold for individual response in patient‐reported outcomes (PROs) in patients with rheumatoid arthritis.MethodsWe used an analysis of variance model in patients on stable therapy (discovery cohort) to establish critical differences (dcrit) for the minimum change associated with a significant individual patient response (beyond normal variation) in the PRO measures of pain (0–10), fatigue (0–10), and function (Funktionsfragebogen Hannover questionnaire; 0–100). We then evaluated PRO responses in patients initiating adalimumab in a noninterventional study (treatment cohort).ResultsIn the discovery cohort (n = 700), PROs showed excellent long‐term retest reliability. The minimum change that exceeded random fluctuation was conservatively determined to be 3 points for pain, 4 points for fatigue, and 16 points for function. In the treatment cohort (n = 2,788), 1,483 patients (53.2%) achieved a significant individual therapeutic response as assessed by Disease Activity Score in 28 joints (DAS28)–dcrit (≥1.8 points) after 12 months of adalimumab treatment; 68.5% of patients with a DAS28‐dcrit response achieved a significant improvement in pain, whereas approximately 40% achieved significant improvements in fatigue or function. Significant improvements in all 3 PROs occurred in 22.7% of patients; 22.8% did not have any significant PRO responses. In contrast, significant improvements in all 3 PROs occurred in only 4.4% of 1,305 patients who did not achieve a DAS28‐dcrit response at month 12, and 59.1% did not achieve any significant PRO responses.ConclusionThe establishment of critical differences in PROs distinguishes true responses from random variation and provides insights into appropriate patient management.
Correlations of Medial Joint Space Width on Fixed‐Flexed Standing Computed Tomography and Radiographs With Cartilage and Meniscal Morphology on Magnetic Resonance Imaging
Authors: Segal N. A. , Frick E. , Duryea J. , Roemer F. , Guermazi A. , Nevitt M. C. , Torner J. C. , Felson D. T. , Anderson D. D. 
Published: March 2016

ObjectiveTo assess whether medial tibiofemoral joint space width (JSW) on 3‐dimensional (3‐D) standing computed tomography (SCT) correlates more closely with magnetic resonance imaging cartilage morphology (CM) and meniscal scores than does radiographic 2‐D JSW.MethodsParticipants in the Multicenter Osteoarthritis Study, who had standing fixed‐flexion posteroanterior knee radiographs, were recruited. Medial tibiofemoral 3‐D JSW on SCT and 2‐D JSW on fixed‐flexion radiographs were compared with medial tibiofemoral cartilage and meniscal morphology using the Whole‐Organ Magnetic Resonance Imaging Score (WORMS). Associations between the area of the articular surface with 3‐D JSW <2.5 mm on SCT, radiographic minimal 2‐D JSW, and the WORMS‐CM and meniscal scores were assessed using Spearman's rho.ResultsFor the 19 participants included (33 knees), mean ± SD age was 66.9 ± 5.4 years, body mass index was 29.5 ± 4.4 kg/m2, 42.1% of participants were female, and the Kellgren/Lawrence grades were 0 (21.2%), 1 (36.4%), 2 (18.2%), and 3 (24.2%). The articular surface area with 3‐D JSW <2.5 mm on SCT correlated with WORMS‐CM scores for the central medial tibia (rs = 0.84, P < 0.001), central medial femur (rs = 0.60, P < 0.007), and posterior medial meniscal tear (rs = 0.39, P < 0.026), as did other cut points for 3‐D JSW. Correlations with radiographic minimal 2‐D JSW were −0.66, −0.52, and −0.40, respectively, differing from SCT only for tibial cartilage (P = 0.001).ConclusionGreater surface area with a low JSW, measured by SCT, correlates more strongly with the severity of tibial cartilage lesions, while correlating with medial femoral cartilage and meniscal damage to a similar extent as radiographic minimal JSW. SCT may enable valid stratification of participants in clinical trials, through quickly and inexpensively characterizing osteoarthritis features.