The force-restore method revisited     

Samuel Y. K. Yee 《Boundary-Layer Meteorology》1988,43(1-2):85-90

The so-called ‘force-restore method’ has been used with considerable success in numerical weather prediction models to simulate diurnal variations of ground temperature. This note demonstrates that the force-restore equation is no more nor less than an approximation to the surface-energy-balance equation. The applicability of the method to the case of multi-component heating functions and to the case in which the soil is covered by a litter layer is discussed.  相似文献   

Limestone deposits and small-scale production of lime in Nigeria     

Samuel A. Ola 《Engineering Geology》1977,11(2):127-137

A general survey of limestone deposits in Nigeria is presented. From these deposits five locations representing the geographical distribution of these deposits were selected and hydrated lime prepared from them. An A-7-6 lateritic soil was stabilized with these locally prepared hydrated limes as well as a commercial lime and the results of unconfined compression, CBR and optimum dry density compared. The results show that the locally prepared limes are not inferior to the commercial limes for soil stabilization and strength characteristics. The results also show that because of the low contents of MgO, the limestones were not sensitive to overheating.  相似文献   

Management application of an empirical model of sardine–climate regime shifts     

Samuel. F. Herrick Jr.  Jerrold. G. Norton  Janet E. Mason  Cindy Bessey 《Marine Policy》2007

In previous work, we show that accumulated anomalies of physical indices are proportional to California sardine landings and that the accumulated anomaly curves change the sign of their slope, showing maxima (minima) when climate is favorable (unfavorable) to successful completion of the sardine life cycle change. Here, we find unique time series characteristics of the periods when the climate changed for sardines in the 1930–2004 period. Only one 50–70 year cycle is examined but the consistency of the dominant signals in measurements taken independently within the sardine's environment at locations separated by thousands of kilometers, supports the argument that the events affecting the ocean-climate of the California Current region and consequently sardine life-cycle are large-scale and persist over multi-decadal periods. Year-to-year monitoring of the climate regime-state in the physical environment and its accumulating effects on sardine populations is also described. The ability to analyze climate shifts and monitor their effects on the sardine populations can reduce uncertainty in making resource management, social and business decisions. Possible effects of management decisions affecting transboundary fisheries issues within United States (US) and between the US and its Pacific neighbors are clarified. The methods presented will add an analysis of low-frequency events to the current management oriented analyses of interannual events, which are part of the existing Pacific Fishery Management Council sardine management plan.  相似文献   

Ethnic and economic regions in Slovakia: A statistical and visual exploration of contemporary patterns     

Samuel M. Otterstrom 《GeoJournal》2000,52(2):139-147

When Czechoslovakia was formed after World War I from the remains of the Austro-Hungarian Empire, the national boundaries imposed at the time did not accurately portray the areal extent of some ethnic groups. This was particularly true for the Hungarian minority which was established along the southern border of Slovakia. Because of this boundary arrangement, ethnic and economic divisions have resulted within Czechoslovakia and have continued in the new state of Slovakia. This paper analyzes the contemporary regional extent of the major ethnic groups in Slovakia at the district and commune levels. It also analyzes these ethnic patterns in light of a number of economic characteristics. Methods include mapping and analysis of various statistical tests using 1991 Czechoslovak census data. A strong relationship between Hungarian communes and agricultural employment is shown as well as a connection between employment in industry and Slovak ethnic regions. These findings suggest that the Hungarian minority has experienced a substantial geopolitical shift from the group in power to a peripheral society within Slovakia that continues to exhibit higher levels of agricultural reliance than the majority of ethnic Slovakian regions.  相似文献   

Thermal Remote Sensing of Near Surface Environmental Variables: Application Over the Oklahoma Mesonet   总被引：1，自引：0，他引：1  

Kevin P. Czajkowski  Samuel N. Goward  Stephen J. Stadler  Anita Walz 《The Professional geographer》2000,52(2):345-357

Many recent studies have applied satellite remote sensing data to large‐scale hydrologic and biospheric modeling. It is widely accepted that the thermal infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) have the potential to estimate land surface conditions, such as surface temperature, near surface air temperature, and near surface water vapor. In this study, algorithms to estimate all three variables are presented and applied to an area covering the state of Oklahoma for a six day period in August, 1994. The results were validated using ground observations from the 111 station Oklahoma Mesonet. Validation of the remote sensing algorithms with Mesonet observations produced comparable results to previous validation studies. In addition, the validation process revealed inadequacies in thermal modeling that had not been detected in previous validation studies leading to the development of a new approach to estimate atmospheric water vapor.  相似文献   

Vertical structure of the stable boundary layer detected by RASS-SODAR and in-situ measurements in SABLES 2006 field campaign   总被引：1，自引：0，他引：1  

Samuel Viana  Carlos Yagüe  Gregorio Maqueda 《Acta Geophysica》2012,60(5):1261-1286

Data from the SABLES 2006 field campaign are used in order to analyse some of the main processes present along the nocturnal periods: surface-based inversions, low level jets, katabatic winds, wave-like motions, pressure perturbations, etc. These processes have an important influence on the vertical structure (both thermal and dynamical) of the atmospheric boundary layer, and can be better described with the synergetic combination of RASS-SODAR data and in-situ measurements (such as sonic anemometer data and high-resolution pressure series from microbarometers). It is shown how the different air masses and their evolution are easily identified when pressure and RASS-SODAR wind and temperature data are presented together. Likewise, periodic pressure fluctuations observed in the surface array of microbarometers reveal the existence of gravity wave motions whose propagation is better understood after locating the wave ducting layers with the help of RASS-SODAR average wind ant temperature profiles.  相似文献   

Use of a Sodar to Improve the Forecast of Fogs and Low Clouds on Airports     

Alain Dabas  Samuel Remy  Thierry Bergot 《Pure and Applied Geophysics》2012,169(5-6):769-781

A sodar was deployed at Roissy–Charles de Gaulle airport near Paris, France, in 2008 with the aim of improving the forecast of low visibility conditions there. During the winter of 2008–2009, an experiment was conducted that showed that the sodar can effectively detect and locate the top of fog layers which is signaled by a strong peak of acoustic reflectivity. The peak is generated by turbulence activity in the inversion layer that contrasts sharply with the low reflectivity recorded in the fog layer below. A specific version of the 1D-forecast model deployed at Roissy for low visibility conditions (COBEL-ISBA) was developed in which fogs’ thicknesses are initialized by the sodar measurements rather than the information derived from the down-welling IR fluxes observed on the site. It was tested on data archived during the winters of 2008–2009 and 2009–2010 and compared to the version of the model presently operational. The results show a significant improvement—dissipation times of fogs are better predicted.  相似文献   

Converted‐wave beam migration with sparse sources or receivers          下载免费PDF全文

Lorenzo Casasanta  Samuel H. Gray 《Geophysical Prospecting》2015,63(3):534-551

Gaussian beam depth migration overcomes the single‐wavefront limitation of most implementations of Kirchhoff migration and provides a cost‐effective alternative to full‐wavefield imaging methods such as reverse‐time migration. Common‐offset beam migration was originally derived to exploit symmetries available in marine towed‐streamer acquisition. However, sparse acquisition geometries, such as cross‐spread and ocean bottom, do not easily accommodate requirements for common‐offset, common‐azimuth (or common‐offset‐vector) migration. Seismic data interpolation or regularization can be used to mitigate this problem by forming well‐populated common‐offset‐vector volumes. This procedure is computationally intensive and can, in the case of converted‐wave imaging with sparse receivers, compromise the final image resolution. As an alternative, we introduce a common‐shot (or common‐receiver) beam migration implementation, which allows migration of datasets rich in azimuth, without any regularization pre‐processing required. Using analytic, synthetic, and field data examples, we demonstrate that converted‐wave imaging of ocean‐bottom‐node data benefits from this formulation, particularly in the shallow subsurface where regularization for common‐offset‐vector migration is both necessary and difficult.  相似文献   

Methods for descriptive factor analysis of multivariate geostatistical data: a case-study comparison     

Samuel D. Oman  Bella Vakulenko-Lagun  Michael Zilberbrand 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(4):1103-1116

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Biodegradation of the Antituberculosis Drug Isoniazid in the Aquatic Environment          下载免费PDF全文

Samuel Sasu  Jörg Metzger  Martin Kranert  Klaus Kümmerer 《洁净——土壤、空气、水》2015,43(2):166-172

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