Passive microwave remote sensing of the historic February 2010 snowstorms in the Middle Atlantic region of the USA     

James L. Foster  Gail Skofronick‐Jackson  Huan Meng  James R. Wang  George Riggs  Paul J. Kocin  Benjamin T. Johnson  Judah Cohen  Dorothy K. Hall  Son V. Nghiem 《水文研究》2012,26(22):3459-3471

The snowfall in the Baltimore/Washington metropolitan area during the winter of 2009/2010 was unprecedented and caused serious snow‐related disruptions. In February 2010, snowfall totals approached 2 m, and because maximum temperatures were consistently below normal, snow remained on the ground the entire month. One of the biggest contributing factors to the unusually severe winter weather in 2009/2010, throughout much of the middle latitudes, was the Arctic Oscillation. Unusually high pressure at high latitudes and low pressure at middle latitudes forced a persistent exchange of mass from north to south. In this investigation, a concerted effort was made to link remotely sensed falling snow observations to remotely sensed snow cover and snowpack observations in the Baltimore/Washington area. Specifically, the Advanced Microwave Scanning Radiometer onboard the Aqua satellite was used to assess snow water equivalent, and the Advanced Microwave Sounding Unit‐B and Microwave Humidity Sounder were employed to detect falling snow. Advanced Microwave Scanning Radiometer passive microwave signatures in this study are related to both snow on the ground and surface ice layers. In regard to falling snow, signatures indicative of snowfall can be observed in high frequency brightness temperatures of Advanced Microwave Sounding Unit‐B and Microwave Humidity Sounder. Indeed, retrievals show an increase in snow water equivalent after the detection of falling snow. Yet, this work also shows that falling snow intensity and/or the presence of liquid water clouds impacts the ability to reliably detect snow water equivalent. Moreover, changes in the condition of the snowpack, especially in the surface features, negatively affect retrieval performance. Copyright © 2011. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

NOAA gulf of Mexico status and trends program: Trace organic contaminant distribution in sediments and oysters     

T. L. Wade  E. L. Atlas  J. M. Brooks  M. C. Kennicutt  R. G. Fox  J. Sericano  B. Garcia-Romero  D. DeFreitas 《Estuaries and Coasts》1988,11(3):171-179

Polynuclear aromatic hydrocarbons (PAH), chlorinated pesticides, and polychlorinated biphenyls (PCB) concentrations were determined in sediment and oysters to provide information on the current status of the concentration of these contaminants in Gulf of Mexico coastal areas removed from point sources of input. Coprostanol analyses of sediments showed that anthropogenic materials are associated with the sediments at all 153 stations sampled. The levels of contaminants encountered are low compared with areas of known contamination. Average PAH concentrations are nearly the same in oysters and sediments, although the molecular weight distribution is different. Average DDT and PCB concentrations are higher by a factor of 10 to 130 in oysters as compared to sediments. Continued sampling and analyses will allow for long-term trends in the concentrations of these contaminants to be determined.  相似文献   

Subsurface transport in water and gas     

Benjamin Ross  Steven Amter 《Engineering Geology》1989,26(4):373-403

Current designs for nuclear-waste repositories rely primarily upon subsurface geologic barriers for long-term containment. Because water and air are generally considered to be the mechanisms most likely to transport radioactivity to the surface environment, flow and transport models are important tools in repository assessment. Most models assume that the geologic medium can be treated as a continuum. A substantial body of recent work has focused on applying these models to difficult-to-solve problems, such as the simulation of variably dense or variably saturated flow and transport, large and complex flow systems, sharp solute concentration fronts, and fractured rock systems. The complex chemical interactions between the transport fluid and solid particles within the system have been analyzed using geochemical flow models, most of which assume that the system is at chemical equilibrium. The role of colloids in contaminant transport is a relatively new area of research. The large-scale effects of small-scale variability within the geologic system have been the subject of intense investigation. Inherent limitations of the continuum approach have prompted the design of models in which the flow occurs in discrete fractures. The difficulty and complexity of simulating transport has led to the development of network transport models, which represent the flow field as a series of 1-D path segments. The widespread use of models for prediction and analysis has prompted investigations of their reliability and relative merits.  相似文献   

SCIENTIFICALLY CREDIBLE SITE-SPECIFIC SOIL CLEANUP LEVELS TO PROTECT GROUND WATER     

D. A. Belluck  S. L. Benjamin 《Ground water》1994,32(6):882-883

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Tidal river sediments in the Washington,D.C. area. III. Biological effects associated with sediment contamination     

Christian E. Schlekat  Beth L. McGee  Eli Reinharz  David J. Velinsky  Terry L. Wade 《Estuaries and Coasts》1994,17(2):334-344

Sediment toxicity and benthic macroinvertebrate community structure were measured as one component of a study cohceived to determine the distribution and effect of sediment contamination in tidal freshwater portions of the Potomac and Anacostia rivers in the Washington, D.C., area. Samples were collected at 15 sites. Analyses included a partial life cycle (28 d) whole sediment test using the amphipod Hyalella azteca (Talitridae) and an assessment of benthic community structure. Survival and growth (as estimated by amphipod length) were experimental endopoints for the toxicity test. Significant mortality was observed in 5 of 10 sites in the lower Anacostia River basin and at the main channel Potomac River site. Sublethal toxicity, as measured by inhibition of amphipod growth, was not observed. Toxicity test results were in general agreement with synoptically measured sediment contaminant concentrations. Porewater total ammonia (NH₃+NH₄ ⁺) appears to be responsible for the toxicity of sediments from the Potomac River, while correlation analysis and simultaneously extracted metals: acid volatile sulfide (SEM∶AVS) results suggest that the toxicity associated with Anacostia River sediments was due to organic compounds. Twenty-eight macroinvertebrate taxa were identified among all sites, with richness varying from 5 to 17 taxa per site. Groups of benthic assemblages identified by group-average cluster analysis exhibited variable agreement with sediment chemical and sediment toxicity results. Integration of toxicological, chemical, and ecological components suggests that adverse environmental effects manifest in the lower Anacostia River benthos result from chemical contamination of sediment.  相似文献   

Global gravitational changes due to atmospheric mass redistribution as observed by the Lageos nodal residual   总被引：4，自引：0，他引：4  

Benjamin Fong Chao  Richard Eanes 《Geophysical Journal International》1995,122(3):755-764

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Geophysical analysis of zonal tidal signals in length of day   总被引：5，自引：0，他引：5  

Benjamin Fong Chao  James B. Merriam  Yoshiaki Tamura 《Geophysical Journal International》1995,122(3):765-775

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Changes in global gravitational energy induced by earthquakes   总被引：1，自引：0，他引：1  

Benjamin Fong Chao  Richard S. Gross  Da-Nan Dong 《Geophysical Journal International》1995,122(3):784-789

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Weighting of Observed Heads for the Inverse Problem     

Benjamin Ross 《Ground water》1984,22(5):569-572

In using least-squares parameter estimation techniques to solve for hydrogeologic parameters, one may use a weighting function to reflect differing reliabilities of head measurements. In studies published to date, the weighting function has been used in an ad boc manner or not at all. The inverse square of the observed hydraulic gradient, adjusted to reflect the modeler's perception of geologic heterogeneity and data reliability, is typically an appropriate weighting function.  相似文献   

The antiferromagnetic-paramagnetic transition in αFe2O3 in the single prism approximation of the cluster variation method     

Benjamin Burton  Ryoichi Kikuchi 《Physics and Chemistry of Minerals》1984,11(3):125-131

The single prism approximation SPA of the cluster variation method has been used to model the antiferromagnetic-paramagnetic transition in hematite. This calculation yields insight into the accuracy of the SPA and other approximate methods for modeling order-disorder phenomena. Published values of the magnetic coupling constants were used to calculate the Néel temperature, sublattice magnetization, and magnetic specific heat. The calculated Néel temperature is found to be 1.21 times the observed value, as compared to 1.36 times observed for a mean field theory approximation, an improvement that reflects the superior treatment of configurational entropy in the SPA. Qualitative to semiquantitative agreement is obtained between observed and calculated values for sublattice magnetization and magnetic specific heat; however we find that previously published values for the magnetic specific heat are too large by a factor of two.  相似文献