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31.
ABSTRACTAdvances in open data science serve large-scale model developments and, subsequently, hydroclimate services. Local river flow observations are key in hydrology but data sharing remains limited due to unclear quality, or to political, economic or infrastructure reasons. This paper provides methods for quality checking openly accessible river-flow time series. Availability, outliers, homogeneity and trends were assessed in 21 586 time series from 13 data providers worldwide. We found a decrease in data availability since the 1980s, scarce open information in southern Asia, the Middle East and North and Central Africa, and significant river-flow trends in Africa, Australia, southwest Europe and Southeast Asia. We distinguish numerical outliers from high-flow peaks, and integrate all investigated quality characteristics in a composite indicator. We stress the need to maintain existing gauging networks, and highlight opportunities in extending existing global databases, understanding drivers for trends and inhomogeneity, and in innovative acquisition methods in data-scarce regions. 相似文献
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The NASA Office of Space Science has established a series of archivalcenters where science data acquired through its space science missionsis deposited. The availability of high quality data to the generalpublic through these open archives enables the maximization of sciencereturn of the flight missions. The Astrophysics Data Centers CoordinatingCouncil, an informal collaboration of archival centers, coordinates datafrom five archival centers distiguished primarily by the wavelength rangeof the data deposited there. Data are available in FITS format. Anoverview of NASA's data centers and services is presented in this paper.A standard front-end modifyer called Astrowbrowse is described. Othercatalog browsers and tools include WISARD and AMASE supported by theNational Space Scince Data Center, as well as ISAIA, a follow on toAstrobrowse. 相似文献
34.
近14 a也门降水异常的气候特征 总被引:2,自引:0,他引:2
利用1990-2003年也门7个测站降水资料,在分析近148也门降水季节变化特征的基础上,着重分析了也门夏季降水的年际变化特征。结果表明,也门降水异常的季节变化明显,异常在4-9月最大,尤其是7-9月,异常峰值所在月呈现出较明显的提早趋势;近148也门夏季降水呈现出增加的趋势,90年代末该趋势加大;近148也门夏季降水存在38和78左右的显著振荡周期。 相似文献
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J.F. Kerridge I.R. Kaplan C.C. Kung D.A. Winter D.L. Friedman D.J. DesMarais 《Geochimica et cosmochimica acta》1978,42(4):391-402
Analytical techniques of improved sensitivity have revealed details of the concentrations and isotopic compositions of light elements for a comprehensive suite of samples from the Apollo 12 regolith. These samples show a wide spread in maturity, although maximum contents observed for solar wind elements are less than observed at other sites, possibly reflecting relative recency of craters at the Apollo 12 site. Isotopic composition of nitrogen is consistent with the idea that 15N/14N in the solar wind has increased with time, at least a major part of this increase having occurred in the past 3.1 Gyr. Sulfur isotope systematics support a model in which sulfur is both added to the regolith, by meteoritic influx and lost, by an isotopically selective process. Most soils from this site are heavily contaminated with terrestrial carbon. 相似文献
37.
Several isoprenoid compounds were isolated from a heat-treated marine sediment in the southern California continental shelf (from Tanner Basin) which were not present in the original sediment. Among the compounds identified were: phytol, dihydrophytol, C18-isoprenoid ketone, phytanic and pristanic acids, C19- and C20-monoolefins, and the alkanes 2,6,10-trimethylpentadecane, pristane and phytane. The significance and possible routes leading to these compounds is discussed. 相似文献
38.
Recent sediments from Tanner Basin (off southern California) and Bandaras Bay (in Gulf of California) have been analyzed for normal, isoprenoid and steroidal alcohols using chromatographic (column, GLC, TLC), and spectroscopic (u.v., i.r., MS) methods, prior to and after heat-treatment (from 65 to 150°C). Normal saturated alcohols (C14-C24) and monounsaturated alcohols (C22-C24) were identified, as well as the isoprenoid alcohols, phytol and dihydrophytol.Two series of sterols (Δ5 and Δ7) were found in Tanner Basin, and Δ5-sterols and triterpenes, in Bandaras Bay sediment. Sterols from both sediments contained the corresponding stanols. 相似文献
39.
P.T. Crisp S. Brenner M.I. Venkatesan E. Ruth I.R. Kaplan 《Geochimica et cosmochimica acta》1979,43(11):1791-1801
Particulate matter was collected during September–October, 1977, in particle traps suspended 30–60 m above the floor of San Nicolas, Santa Barbara, Santa Monica and San Pedro Basins, off the coast of southern California. The trap particulates were analyzed for C15–C35 hydrocarbons using gas chromatography (GC) and GC-mass spectrometry. Kerogens and humic acids were characterized by H/C, N/C, δ13C, δ15N and δ34S ratios, and by electron-spin resonance. Hydrocarbons arising from fresh and weathered petroleum, marine autochthonous and terrestrial sources were identified. The rates of petroleum deposition during the collection period followed the order: San Nicolas Basin < Santa Barbara Basin ~ Santa Monica Basin < San Pedro Basin, with the largest amount of weathered petroleum being deposited in San Pedro Basin. The rates of petroleum deposition are correlated more strongly with human activities such as shipping, and the discharge of municipal and industrial wastes, than with natural submarine oil seepage. Analyses of kerogens and humic acids indicate that the majority of the organic matter in the trap particulates is of marine origin. The water column overlying Santa Barbara Basin appears to have the highest marine productivity of the four basins studied. 相似文献
40.
Growing and resting cell suspensions of Baker's yeast (Saccharomyces cerevisiae) were permitted to metabolize sulfite and sulfate under a variety of environmental conditions. Enrichment of S32 in the H2S released during reduction of sulfate under growing conditions was consistently lower (δS34 < ?25%.) than enrichment during reduction of sulfite under similar conditions (δS34 ~ ?30 to ?50%.). Yeast cells harvested from a sulfite medium released small quantities of H2S when suspended in glucose-sulfate solution; cells from a sulfate growth medium did not. The enrichment of H2S in S32 by sulfite-grown resting cells suspended in either SO2?4 or SO2?3 solutions was about 10%.in less than the maximum obtained during growth on sulfite. Isotopic fractionation was always significantly less in assimilated, than in dissimilated sulfur. 相似文献