K. Arnold 《Journal of Geodesy》1968,42(1):97-101

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NOAA卫星探测数据对B-模式分析预报系统性误差的影响   总被引：1，自引：1，他引：1       下载免费PDF全文

王宗皓  毛建平  黄继红  A. Gruber  A. Thomasell  T. S. Chen 《Acta Meteorologica Sinica》1993,51(1):21-33

本文报告极轨气象卫星探测数据对B-模式的海平面气压场预报和500hPa高度预报的系统性误差的影响.主要结果是:(1)B-模式预报海平面气压的强度偏弱,即高压系统太低,低压太高;(2)500hPa高度预报的系统性误差情况不如海平面气压场误差情况明显.但也能发现槽区的高度预报不够低,而脊区的高度预报不够高;(3)应用卫星数据对B-模式分析预报系统的预报有正作用,对海洋上的地面低压和500hPa槽区附近的系统性误差有明显减小,但对其它地区天气系统预报的正负影响参差不齐,其作用难下结论。  相似文献   

An evaluation of the apparent dissociation constants of carbonic acid in seawater     

Taro Takahashi  Peter Kaiteris  Wallace S. Broecker  Arnold E. Bainbridge 《Earth and Planetary Science Letters》1976,32(2):458-467

The internal consistency of five sets of apparent dissociation constants of carbonic acid in seawater obtained by Buch (1951), Lyman (1956), Edmond and Gieskes (1970), Hansson (1973) and Mehrbach et al. (1973) have been tested using the GEOSECS Atlantic data for the total alkalinity, the total CO₂ concentration and the partial pressure of CO₂. As a measure of the consistency for each of the five sets of the dissociation constants with the data, the 77 measured values of the partial pressure of CO₂ have been compared with those calculated from the alkalinity and total CO₂ values determined for these samples. It has been found that: (1) the apparent dissociation constants of Lyman (1956), Hansson (1973) and Mehrbach et al. (1973) appear to be internally consistent with the data, whereas those of Buch (1951) and of Edmond and Gieskes (1970) appear to be markedly inconsistent with the GEOSECS data; and (2) on the basis of a statistical analysis of the data grouped in three temperature ranges, the dissociation constants of Lyman (1956) and of Mehrbach et al. (1973) appear to be most satisfactory.  相似文献   

Aspèct Isotopique δ34S‰ d'un Processus de Mobilisation et de Réconcentration de Sulfures en Amas à Structure Filoniénne     

M. Arnold  J. Guha 《Mineralium Deposita》1980,15(3):361-381

Résumé Beaucoup de minéralisations sulfurées filoniennes sont encaissées dans des formations qui contiennent les mêmes éléments mais à l'état disséminé. En ce cas, on admet généralement que ces éléments ont été mobilisés et reconcentrés dans des structures tectoniques distensives. Le même mécanisme peut encore être envisagé quand de telles minéralisations sont spatialement éloignées des formations réservoirs de soufre et de métaux. Connaissant la composition isotopique des sulfures filoniens ainsi que les conditions physico-chimiques de leur dépôt il est possible de calculer la valeur théorique de la composition isotopique des sulfures du réservoir. Celle-ci peut alors être comparée aux compositions isotopiques effectives des sulfures provenant des différents réservoirs potentiels dans le but de déterminer quel est le réservoir de soufre et de métaux le plus probable. Une série d' analyses isotopiques a été entreprise sur les sulfures des minéralisations de Henderson et de Campbell Chibougamau Main Mine. Ces minéralisations du type Cu-Au sont en relation spatiale avec des zones de cisaillement développées dans le complexe du Lac Doré. La composition isotopique moyenne de la pyrite de Henderson vaut –2.9. Cette valeur est très proche de la moyenne des compositions isotopiques de la pyrite de Chibougamau Main Mine (–2.8). La composition isotopique moyenne de la chalcopyrite de Henderson est de –3.2. En se fondant sur le modèle thermodynamique proposé d'une part, sur les compositions isotopiques de la pyrite et de la chalcopyrite d'une minéralisation stratiforme encaissée dans le réservoir présumé d'autre part, il est possible de conclure que les sulfures des minéralisations filoniennes ont été remobilisés des formations volcano-sédimentaires.

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Many sulphide concentrations occur in formations containing the same elements in a disseminated state. It is generally admitted that these elements may be mobilised and reconcentrated into open spaces. The same mechanism has been envisaged in cases where vein deposits are spatially separated from the rocks which acted as a reservoir for sulphur and metals. Knowing the isotopic composition of the sulphide from the veins as well as the physico-chemical conditions of deposition, the theoretical value of the sulphur isotopic composition of the reservoir can be calculated and this can be compared with the values of the sulphides from the different reservoirs in order to indicate the most likely source. A series of isotopic analyses were untertaken on the sulphides from Henderson and Campbell Chibougamau Main Mines. These two deposits belong to the Cu-Au type of mineralisation associated with shear zones within the Lac Doré Complex. The mean isotopic composition of pyrite at Henderson is –2.9 which is close to the mean values measured at Campbell Chibougamau Main Mine (–2.8). The mean value of the chalcopyrite from the Henderson Mine is –3.2. Different possibilities concerning the provencance of sulphur are discussed. Based on existing thermodynamic model and on a set of new isotopic datas (pyrite and chalcopyrite) from volcanogenic mineralisation, it is possible to conclude that measured values correspond to mobilised volcanogenic sulfur.

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Neuere Veröffentlichungen     

Arnold Schumacher  Hans Ermel  G. Dietrich 《Ocean Dynamics》1954,7(5-6):203-207

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A GIS-Coupled Hydrological Model System for the Watershed Assessment of Agricultural Nonpoint and Point Sources of Pollution   总被引：9，自引：0，他引：9  

Mauro Di Luzio  Raghavan Srinivasan  Jeffrey G Arnold 《Transactions in GIS》2004,8(1):113-136

This paper introduces AVSWAT, a GIS based hydrological system linking the Soil and Water Assessment Tool (SWAT) water quality model and ArcView“ Geographic Information System software. The main purpose of AVSWAT is the combined assess‐ment of nonpoint and point pollution loading at the watershed scale. The GIS component of the system, in addition to the traditional functions of data acquisition, storage, organization and display, implements advanced analytical methods with enhanced flexibility to improve the hydrological characterization of a study watershed. Intuitive user friendly graphic interfaces, also part of the GIS component, have been developed to provide an efficient interaction with the model and the associated parameter databases, and ultimately to simplify water quality assessments, while maintaining and increasing their reliability. This is also supported by SWAT, the core of the system, a complex, conceptual, hydrologic, continuous model with spatially explicit parameterization, building upon the United State Department of Agriculture (USDA) modeling experience. A step‐by‐step example application for a watershed in Central Texas is also included to verify the capability and illustrate some of the characteristics of the system which has been adopted by many users around the world.  相似文献   

Scaling Variances of Scalars in a Convective Boundary Layer Under Different Entrainment Regimes     

Arnold F. Moene  Berenice I. Michels  Albert A. M. Holtslag 《Boundary-Layer Meteorology》2006,120(2):257-274

For the presentation and analysis of atmospheric boundary-layer (ABL) data, scales are used to non-dimensionalise the observed quantities and independent variables. Usually, the ABL height, surface sensible heat flux and surface scalar flux are used. This works well, so long as the absolute values of the entrainment ratio for both the scalar and temperature are similar. The entrainment ratio for temperature naturally ranges from −0.4 to −0.1. However, the entrainment ratio for passive scalars can vary widely in magnitude and sign. Then the entrainment flux becomes relevant as well. The only customary scalar scale that takes into account both the surface flux and the entrainment flux is the bulk scalar scale, but this scale is not well-behaved for large negative entrainment ratios and for an entrainment ratio equal to −1. We derive a new scalar scale, using previously published large-eddy simulation results for the convective ABL. The scale is derived under the constraint that scaled scalar variance profiles are similar at those heights where the variance producing mechanisms are identical (i.e., either near the entrainment layer or near the surface). The new scale takes into account that scalar variance in the ABL is not only related to the surface flux of that scalar, but to the scalar entrainment flux as well. Furthermore, it takes into account that the production of variance by the entrainment flux is an order of magnitude larger than the production of variance by the surface flux (per unit flux). Other desirable features of the new scale are that it is always positive (which is relevant when scaling standard deviations) and that the scaled variances are always of order 1–10.  相似文献   

Surveying Ground Water Level Using Remote Sensing: An Example over the Seco and Hondo Creek Watershed in Texas     

Pei-yu Chen  Jeffrey G. Arnold  Raghavan Srinivasan  Martin Volk  Peter M. Allen 《Ground Water Monitoring & Remediation》2006,26(2):94-102

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Acoustic tomography in the atmospheric surface layer     

A. Ziemann  K. Arnold  A. Raabe 《Annales Geophysicae》1998,17(1):139-148

Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell’s law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique) is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.  相似文献   

The end of moai quarrying and its effect on Lake Rano Raraku, Easter Island     

Henri J. Dumont  Christine Cocquyt  Michel Fontugne  Maurice Arnold  Jean-Louis Reyss  Jan Bloemendal  Frank Oldfield  Cees L.M. Steenbergen  Henk J. Korthals  Barbara A. Zeeb 《Journal of Paleolimnology》1998,20(4):409-422

We reconstruct aspects of the history of Easter Island over the last 4-5 centuries based on the study of a core from Rano Raraku Lake, situated in the crater that contains the quarry of the island's giant statues or moai. We use microfossils of plants and animals to identify five zones. The last three of these are separated by waves of immigration from South America and from the subantarctic. We argue that the first or South American wave, dated to the second half of the 14th century, may represent a visit by South American Indians. Magnetic information, pollen, diatoms, chrysophyte stomatocysts and fossil plant pigments reveal a synchronism between the South American contact and the cessation of moai quarrying. We therefore suggest that Amerindians contributed to the cultural collapse of the island. The second or subantarctic wave may reflect an early European visit to the island, possibly by Cpt. James Cook in 1774, or by Jacob Roggeveen in 1722.  相似文献