Comparisons of modelled and observed climate for impact assessments     

P. J. Robinson  A. N. Samel  G. Madden 《Theoretical and Applied Climatology》1993,48(2-3):75-87

Summary Comparisons between observed and modelled values of surface temperature, surface precipitation and 500 hPa height for the current climate were made for the southeast United States. Daily values and analyses pertinent to impact assessment, were emphasized. For the model, the time-independent 10-year series of values developed by the Geophysical Fluid Dynamics Laboratory general circulation model were used. Observations were drawn from records for various stations and decades within the model grid-cell. Cumulative frequency distributions of temperature indicated both more clustering close to the mean and greater extremes for the model. The model reproduced the seasonal cycle of day-to-day temperature variability, but introduced a phase shift of about four months. One result was an apparent overabundance of hot spells in the model results. For precipitation the model indicated twice as many raindays as were observed, about the same number of days when precipitation exceeded 5 mm, and fewer days with amounts exceeding 10 mm, effectively decreasing the probability of heavy precipitation while enhancing annual totals. In winter the model appeared to represent the results from an aggregation of stations within the grid-cell, but in summer it was closer to individual station results. The model reproduced the seasonal cycle in the height and standard deviation of the 500 hPa surface, with a damped amplitude in both cases.With 9 Figures  相似文献   

Large-scale deformation associated with ridge subduction   总被引：1，自引：0，他引：1  

Eric L. Geist  Michael A. Fisher  David W. Scholl 《Geophysical Journal International》1993,115(2):344-366

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Variability of dissolved organic carbon in sediments of a seagrass bed and an unvegetated area within an estuary in Southern Texas     

Eric T. Koepfler  Ronald Benner  Paul A. Montagna 《Estuaries and Coasts》1993,16(3):391-404

Pore-water dissolved organic carbon (PWDOC) concentrations were examined in vegetated and bare sediments of aHalodule wrightii seagrass bed, and in a mud bottom sediment of a southern Texas estuary. Temporal variability was examined at diel (dawn and noon) and bimonthly time scales. Distribution patterns of PWDOC were compared with physical, chemical, and biological factors thought to exert control on PWDOC. Concentration of PWDOC, bacterial production, and resultant PWDOC turnover times displayed statistically significant spatial and temporal variability. Concentration of PWDOC ranged from 14 mg C 1^?1 to 107 mg C 1^?1 of pore water, or 9–71 μg C cm^?3 wet sediment. PWDOC was more variable and was approximately 5 times higher than DOC concentrations in the water column. Low PWDOC concentrations (mean = 14.6 μg C cm^?3) and high bacterial production rates (mean = 1.92 μg C cm^?3 h^?1) were observed at the mud station, whereas PWDOC concentrations were high (mean = 24.6 μg C cm^?3) and bacterial production rates were low (mean = 0.43 μg C cm^?3 h^?1) at the bare station. PWDOC turnover times (T_t), assuming 50% bacterial growth efficiency (1–840 h) were shortest at the mud station (mean=13 h) and longest at the bare station (mean=180 h). In the overlying water column, T_t values were longer, ranging from 1,000–10,000 h. PWDOC concentrations were 25% higher in vegetated sediments than in neighboring bare sediments. This difference was probably due to inputs of labile photosynthetic excretia, since bacterial production rates in vegetated sediments displayed significant diel variability and were 4 times greater than that of bare sediments. Based upon the entire data set, PWDOC was significantly related to macrofaunal biomass, sediment POC, sediment C:N ratios, and oxygen metabolism, but was significantly correlated only to the latter two variables in stepwise multiple regression. Our findings suggest that organism activities and detrital quality are the major determinants controlling variability in PWDOC.  相似文献   

A Laboratory and Numerical Investigation of Solute Transport in Discontinuous Fracture Systems   总被引：2，自引：0，他引：2  

J. W. Robinson  J. E. Gale 《Ground water》1990,28(1):25-36

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1988 Compilation of Elemental Concentration Data for USGS Basalt BCR-1     

Ernest S. GLADNEY  Elizabeth A. JONES  Eric J. NICKELL  Iwan ROELANDTS 《Geostandards and Geoanalytical Research》1990,14(2):209-359

Concentration data on up to 82 individual constituents in USGS Basalt BCR-1 have been collected from 1395 journal articles and technical reports. These data are summarized in consensus (mean) values with uncertainties expressed as ± one standard deviation. Mean values are also calculated as a function of analytical procedure and all raw data are given in the tables. Recommended values are proposed based upon data criteria used by NIST (National Institute of Standards and Technology, formerly the National Bureau of Standards or NBS).  相似文献   

Complete chemical analyses of metamorphic hornblendes: implications for normalizations,calculated H2O activities,and thermobarometry   总被引：1，自引：0，他引：1  

Michael A. Cosca  Eric J. Essene  Johns R. Bowman 《Contributions to Mineralogy and Petrology》1991,108(4):472-484

Twenty-two hornblendes separated from amphibolites and granulites of the Grenville Orogen of Ontario have been quantitatively analyzed for major and minor elements by electron microprobe, for FeO/Fe₂O₃ by wet chemistry, and for H₂O by manometric measurement as H₂. Hornblende formulae were calculated on the basis of 24O+OH+Cl+F. Most samples are magnesio-hornblendes, ferroan pargasitic hornblendes and ferroan hastingsitic hornblendes, with weight fractions of Fe³⁺/(Fe²⁺+Fe³⁺) ranging from 0.15 to 0.50. An oxy-amphibole component of 0–25 mol%, with an average value of 17 mol%, is obtained for these complete analyses. When compared with structural formulae determined solely from microprobe data, normalization based on 13=Si+Ti+Al+Fe+Mn+Mg cations provides the best approximation to hornblende formulae calculated from the complete analyses. Less satisfactory agreement is obtained from a normalization scheme based on 15=Si+Ti+Al+Fe+Mn+Mg+Ca, while worst agreement is obtained from normalization to 23 oxygens assuming all Fe is Fe²⁺. No normalization scheme based on microprobe data alone consistently replicates the measured FeO, Fe₂O₃, and H₂O; accurate determination of these values requires complete chemical analysies. Ionic solution models previously have been proposed to evaluate the activity of Ca₂Mg₅Si₈ O₂₂(OH)₂(a _Trem) in hornblende for use in equilibria that constrain the activity of H₂O (a _{H 2}O) in igneous and metamorphic rocks. Application of ionic models to typical hornblendes produces low a _Trem (usually<0.01), consequetly yielding extremely low a _{H 2}O. If an oxy-amphibole component is present, the calculated a _Trem and H₂O is further reduced. An oxy-amphibole component of 25% reduces the calculated H₂O activity and that of any hydroxyl-amphibole component by 50% below that calculated with simplified assumptions regarding X _OH in the hydroxyl site (i.e., X _OH=1, or X _OH=1–X _Cl–X _f). Thus, methods of amphibole normalizations appear to have a substantial effect on calculated amphibole and H₂O activites. Before quantitative hornblende thermobarometry can be calibrated and applied, the amounts of FeO, Fe₂O₃ and H₂O must be measured in order to fully characterize hornblende solid solutions.Contribution No. 478 from the Mineralogical Laboratory, University of Michigan  相似文献   

Multilayer Sampling in the Water-Table Region of a Sandy Aquifer     

Edward Kaplan  Sujit Banerjee  Daniel Ronen  Mordeckai Magaritz  Albert Machlin  Michael Sosnow  Eric Koglin 《Ground water》1991,29(2):191-198

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地面对晴空大气热辐射结构的影响     

王鹏举  周秀骥  EricA.Smith  施蕾 《气象学报》1991,49(2):215-221

本文利用1987年美国FIFE资料及1986年6月TIPMEX资料,并利用大气长、短波一维辐射传输数值模式,计算了晴空大气状态下地面辐射参数(地面热辐射温度、地表反照率等)对大气长波冷却率、短波加热率廓线的影响。结果表明,地球表面对大气边界层内的热辐射结构影响很大,特别是在高原地区这种影响尤其显著。  相似文献   

Genesis and solvus relations of submicroscopically intergrown paragonite and phengite in a blueschist from northern California     

Yen-Hong Shau  Melanie E. Feather  Eric J. Essene  Donald R. Peacor 《Contributions to Mineralogy and Petrology》1991,106(3):367-378

Electron microbeam techniques have been used to examine submicroscopically intergrown paragonite, phengite and chlorite from the South Fork Mountain Schist of the Franciscan Terrane of northern California, which was subjected to blueschist facies metamorphism. The sample also contains quartz, albite, lawsonite, and rutile. The subassemblage albite-lawsonite-rutile requires metamorphic conditions on the low-temperature side of the equilibrium albite+lawsonite+rutile=paragonite+sphene+quartz+H₂O (T<200° C and P<7.4 kbars based on thermodynamic data of Holland and Powell 1990). The white micas appear to be optically homogeneous, but back-scattered electron images can distinguish two different micas by their slight difference in contrast. Electron microprobe analyses (EMPA) of micas show Na/(Na+K) ranging from 0.2 to 0.8. The two micas are resolved by transmission electron microscopy (TEM) as packets of phengite and paragonite that range from 20 to several hundred nm in thickness. The compositions, determined by analytical electron microscopy (AEM), constrain the limbs of the phengite-paragonite solvus to values of Na/(Na+K)=<0.02 and 0.97, representing less mutual solid solution than ever reported by EMPA. The textural relations imply that the sheet silicates were derived from reactions between fluids and detrital clays and that they are in an intermediate stage of textural development. We caution that microprobe analyses of apparently homogeneous sheet silicates may yield erroneous data and lead to faulty conclusions using phengite barometry and paragonite-muscovite thermometry, especially in fine-grained rocks that formed at relatively low temperatures. Contribution no. 473 from the Mineralogical Laboratory, Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan, USA  相似文献   

The latitudinal distribution of carbon monoxide across the pacific from California to Antarctica     

Elmer Robinson  David Clark  Wolfgang Seiler 《Journal of Atmospheric Chemistry》1984,1(2):137-149

The results of a research study of the carbon monoxide concentration from California to 90° S, Antarctica are presented. The data both extend and support other research studies of the latitudinal distribution of carbon monoxide in that higher concentrations are evident over the Northern Hemisphere than over the Southern Hemisphere. Carbon monoxide concentrations range between 50 to 60 ppb with a few peaks into the 60s in the latitudinal area south of the ITCZ and values of 80 ppb or higher at latitudes north of Hawaii. A comparison is also made of carbon monoxide and ozone concentrations along the flight tract between California and Antarctica, over the Ellsworth Mountains of Antarctica, and between 78° S and the South Pole. These ozone-carbon monoxide data show statistically significant negative correlations in the upper troposphere and lower stratosphere over Antarctica. It is believed that this is a good indication of mixing across the tropopause.  相似文献