Modelling the Northeast Atlantic circulation: implications for the spring invasion of shelf regions by Calanus finmarchicus     

Harms  I. H.; Heath  M. R.; Bryant  A. D.; Backhaus  J. O.; Hainbucher  D. A. 《ICES Journal of Marine Science》2000,57(6):1694-1707

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Noble gas loss may indicate groundwater flow across flow barriers in southern Nevada     

James M. Thomas  Bryant G. Hudson  Martin Stute  Jordan F. Clark 《Environmental Geology》2003,43(5):568-579

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The Value of Improved ENSO Prediction to U.S. Agriculture     

Andrew R. Solow  Richard F. Adams  Kelly J. Bryant  David M. Legler  James J. O'Brien  Bruce A. McCarl  William Nayda  Rodney Weiher 《Climatic change》1998,39(1):47-60

The economic value of long-range weather prediction is measured by the increase in social welfare arising from the use of the prediction in economic decisionmaking. This paper describes a study of the economic value of ENSO prediction to U.S. agriculture. The interdisciplinary study involved the analysis of data and models from meteorology, plant science, and economics under a framework based on Bayesian decision analysis. The estimated annual value of perfect ENSO prediction to U.S. agriculture is $323 million.  相似文献   

Measuring the effect of overgrazing in the Sonoran Desert   总被引：4，自引：0，他引：4  

Nevin A. Bryant  Lee F. Johnson  Anthony J. Brazel  Robert C. Balling  Charles F. Hutchinson  Louisa R. Beck 《Climatic change》1990,17(2-3):243-264

Long term overgrazing in Mexico has caused a sharp discontinuity in vegetative cover along the international border in the semi-arid Sonoran Desert. The United States side, protected from overgrazing by the Taylor Act since 1934, exhibits longer, more plentiful grasses and less bare soil than adjoining Mexican lands. Satellite- and ground-based datasets were used in a multi-scale examination of the differential radiative and reflective characteristics of the two regimes. The more exposed Mexican landscape dries more rapidly than the United States following summer convective precipitation. After about three days, depletion of soil moisture evokes a period of higher surface and air temperatures in Mexico. Good correspondence was found between remote and in situ measures of surface temperature and biomass.  相似文献   

Hot moments and hot spots of nutrient losses from a mixed land use watershed   总被引：1，自引：0，他引：1  

Qing Zhu  John P. Schmidt  Ray B. Bryant 《Journal of Hydrology》2012

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Sedimentology of Proterozoic cratonic sheet sandstones of the eastern Canadian Shield: Sims Formation,Labrador, Canada     

Michael J. Ware  Richard N. Hiscott 《Precambrian Research》1985,30(1):1-26

The upper lower Proterozoic to middle Proterozoic Sims Formation rests unconformably on lower Proterozoic strata of the Knob Lake Group of the Labrador Trough sequence. The 700 m-thick Sims Formation consists of basal fluvial arkoses and conglomerates (about 100 m) and an upper sheet-like sand body (about 600 m thick) composed of quartz arenites and minor quartz-clast conglomerates. This upper unit is interpreted as beach, shoreface, tidal and shallow-shelf deposits. The lowest 70 m of the quartz arenite unit appear to be of fluvial origin, but probably were formed by reworking of quartzose sands produced in coastal environments during a period of elevated sea level.The lower Sims Formation probably represents molasse shed from either the Hudson or Labrador orogens. Rivers flowed northwest away from these upland areas. The upper part of the Sims Formation records deposition during a period of slow, steady sea-level rise in an ocean that deepened to the west.The Sims Formation outliers are remarkably similar to outliers of the Sakami Formation of northern Quebec, a unit that has a poorly-constrained early to middle Proterozoic age. If these units are correlative, a hypothesis supported mainly by identical facies and facies sequences, then the transgressive quartz arenites would originally have covered an area of at least 200 000 km².  相似文献   

Prediction of imbibition from grain-scale interface movement     

M. Gladkikh  S. Bryant 《Advances in water resources》2007

Processes in porous media governed by capillary forces, such as drainage or imbibition of wetting phase, are of great importance in different branches of soil science, petroleum engineering and hydrology. In this work we describe a new way of modeling imbibition by considering the movement and merger of interfaces at the pore level. The model is based upon a physically consistent dynamic criterion for the imbibition of a single pore originally proposed by Melrose.  相似文献   

The detection and interpretation of hydrogen in fault gases   总被引：1，自引：0，他引：1  

Randolph H. Ware  Christian Roecken  Max Wyss 《Pure and Applied Geophysics》1984,122(2-4):392-402

Hydrogen gas can be released by chemical and mechanical changes in crustal rocks. Once released, it is highly mobile, buoyant, and almost insoluble in groundwater. A fault system may act as a conduit, allowing hydrogen to accumulate in soil gases near a surface expression. Since hydrogen is scarce in ambient air, its presence at elevated levels in soil gases may be a tool for fault mapping. In order to evaluate this tool, we surveyed eleven different faults by measuring the concentration of hydrogen and methane in 2 to 21 soil-gas samples that were collected near each of them. The sense of motion at four of those faults is normal (western United States, Greece), at five it is strike-slip or dip-slip (California, Colorado, Japan), and at two it is thrusting (California). At four of these faults (Hebgen Lake, Yellowstone, Yamasaki, Burro Mountain) maximum concentrations of hydrogen ranged from 80 ppm to 70% and methane from 300 ppm to 5%. All other sites showed ambient levels of both gases, except for one sample taken at Mt. Borah, Idaho, that was 2% methane. From this preliminary study it is not clear whether the presence of hydrogen is correlated uniquely to the location of faults or whether it occurs randomly. The conditions required to produced and accumulate hydrogen are also not clear. Excess hydrogen may well be produced by different mechanisms in different geological regimes. For example, if ferrous hydroxide is present in local rocks, it may react to produce hydrogen. Detailed and extensive studies are needed to clarify the connection between hydrogen and tectonic faulting.  相似文献   

North American farmland protection strategies in retrospect     

C. R. Bryant  Prof. Dr. L. H. Russwurm 《GeoJournal》1982,6(6):501-511

The arenas in which farmland protection strategies have developed in North America vary in terms of perceptions of the farmland resource and the role of planning, and in terms of administrative structures. Administratively, farmland protection strategies have developed in a variety of structures, ranging from the very decentralized ones of many US states to the more centralized, though still mixed, ones found in some Canadian provinces. Farmland protection strategies can thus be investigated in terms of how they address a variety of fundamental issues. Difficult questions are raised by policy evaluation, e.g. are objectives coherent, how do objectives relate to goals and objectives for other land uses and what would have happened in the absence of the program? It is argued that, while it is essential to encourage more analyses of how results, e.g. farmland removal rates, relate to stated objectives, it is equally important to study the decision-making process of implementation to establish both stated and implied objectives and therefore how farmland protection strategies relate to the broader land use planning and management context for other land uses.  相似文献   

Optimization of UAVs-SfM data collection in aeolian landform morphodynamics: a case study from the Gonghe Basin,China     

Wanyin Luo  Mei Shao  Xuehua Che  Patrick A. Hesp  Robert G. Bryant  Changzhen Yan  Zanpin Xing 《地球表面变化过程与地形》2020,45(13):3293-3312

UAVs-SfM (unmanned aerial vehicles-structure-from-motion) systems can generate high-resolution three-dimensional (3D) topographic models of aeolian landforms. To explore the optimization of UAVs-SfM for use in aeolian landform morphodynamics, this study tested flight parameters for two contrasting aeolian landform areas (free dune and blowout) to assess the 3D reconstruction accuracy of the UAV survey compared with field point measurements using differential RTK-GPS (real-time kinematic-global positioning system). The results reveal the optimum UAVs-SfM flight set-up at the free-dune site was: flying height = 74 m, camera tilt angle = −90°, photograph overlap ratio = 85%/70% (heading/sideways). The horizontal/vertical location error was around 0.028–0.055 m and 0.053–0.069 m, respectively, and a point cloud density of 463/m³ was found to generate a clear texture using these flying parameters. For the < 20 m deep blowout the optimum set-up with highest accuracy and the lowest cliff texture distortion was: flying height = 74 m combined camera tilt angle = −90° and −60°, photograph overlap ratio = 85%/70% (heading/sideways), and an evenly distributed GCPs (ground control points) density of 42/km² using these flying parameters. When the depth of the blowouts exceeded 40 m, the optimum flight/survey parameters changed slightly to account for more challenging cliff texture generation: flying height = 80 m (with −90° and −60°combined camera tilt angle), GCPs density = 63/km² to generate horizontal and vertical location error of 0.024 m and 0.050 m, respectively, and point cloud density of 2597.11/m³. The main external factors that affect the successful 3D reconstruction of aeolian landforms using UAVs-SfM are the weather conditions, manipulation errors, and instrument system errors. The UAVs-SfM topographic monitoring results demonstrate that UAVs provide a viable and robust means for aeolian landform morphodynamics monitoring. Importantly, the rapid and high precision 3D reconstruction processes were significantly advanced using the optimal flight parameters reported here. © 2020 John Wiley & Sons, Ltd.  相似文献