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排序方式: 共有233条查询结果,搜索用时 31 毫秒
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Estimating groundwater storage changes in the Mississippi River basin (USA) using GRACE 总被引:7,自引:0,他引:7
Matthew Rodell Jianli Chen Hiroko Kato James S. Famiglietti Joe Nigro Clark R. Wilson 《Hydrogeology Journal》2007,15(1):159-166
Based on satellite observations of Earth’s time variable gravity field from the Gravity Recovery and Climate Experiment (GRACE), it is possible to derive variations in terrestrial water storage, which includes groundwater, soil moisture, and snow. Given auxiliary information on the latter two, one can estimate groundwater storage variations. GRACE may be the only hope for groundwater depletion assessments in data-poor regions of the world. In this study, soil moisture and snow were simulated by the Global Land Data Assimilation System (GLDAS) and used to isolate groundwater storage anomalies from GRACE water storage data for the Mississippi River basin and its four major sub-basins. Results were evaluated using water level records from 58 wells set in the unconfined aquifers of the basin. Uncertainty in the technique was also assessed. The GRACE-GLDAS estimates compared favorably with the well based time series for the Mississippi River basin and the two sub-basins that are larger than 900,000 km2. The technique performed poorly for the two sub-basins that have areas of approximately 500,000 km2. Continuing enhancement of the GRACE processing methods is likely to improve the skill of the technique in the future, while also increasing the temporal resolution. 相似文献
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As the origin of the soft X-ray background, emission of soft X-rays from shocks occurred in the accretion of intergalactic gas onto the Galaxy is studied. Infall of discrete gas clouds cannot explain the diffuse component of soft X-rays. If intergalactic gas rich in heavy elements as the cosmic abundance continously flows into the Galaxy and forms a standing shock surrounding the Galaxy, the line emissions by heavy elements from the shocked gas explain the soft X-ray background. Formation of the high velocity cloud by thermal instability in the shocked gas is also discussed briefly. 相似文献
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A. Schumann A. Muwanga T. Lehto M. Staudt T. Schlüter V. Kato A. Namboyera 《Geology Today》2015,31(2):59-67
Geosites are important and/or unique geological or geographical features of significance. Typically they comprise geological, palaeontological, as well as archaeological sites. Geosites should be regarded as deserving to be preserved and protected, either from the elements or from destructive human activities, both for the community and future generations. A good knowledge of geological heritage, and a healthy respect for it, is an important factor in the holistic approach for sustainable development. Very often, these sites bear a multi‐faceted ‘story’, which may date back from very recent times to billions of years ago. As such, geosites are of great educational and scientific value. In Africa, such sites have not been receiving the attention they deserve. Only a few countries on the continent acknowledge their importance. Within the framework of a Sustainable Management of Mineral Resources Project (SMMRP), geological mapping, geochemical surveys and mineral resources assessment in selected areas of Uganda have been completed under the umbrella of the Geological Survey of Finland (GTK), and the Department of Geological Survey and Mines (DGSM, Uganda). Apart from recording ‘hard‐tough’ geology, 62 geosites were documented in 2010 and 2011. For the first time, such sites have been incorporated in the new geological maps of the country (at a scale of 1: 250 000). It is possible that this is the first time that such places have been shown on geological maps of Africa. Currently, the extreme north‐east of the country is being geologically mapped by DGSM, with the eventuality of more possible geosites being discovered. 相似文献
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Toshihiko Masui Kenichi Matsumoto Yasuaki Hijioka Tsuguki Kinoshita Toru Nozawa Sawako Ishiwatari Etsushi Kato P. R. Shukla Yoshiki Yamagata Mikiko Kainuma 《Climatic change》2011,109(1-2):59-76
Representative Concentration Pathway 6.0 (RCP6) is a pathway that describes trends in long-term, global emissions of greenhouse gases (GHGs), short-lived species, and land-use/land-cover change leading to a stabilisation of radiative forcing at 6.0 Watts per square meter (Wm?2) in the year 2100 without exceeding that value in prior years. Simulated with the Asia-Pacific Integrated Model (AIM), GHG emissions of RCP6 peak around 2060 and then decline through the rest of the century. The energy intensity improvement rates changes from 0.9% per year to 1.5% per year around 2060. Emissions are assumed to be reduced cost-effectively in any period through a global market for emissions permits. The exchange of CO2 between the atmosphere and terrestrial ecosystem through photosynthesis and respiration are estimated with the ecosystem model. The regional emissions, except CO2 and N2O, are downscaled to facilitate transfer to climate models. 相似文献
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We estimate interseismic coupling on the subducting plate interface in the Tokai area, central Japan, by inverting two geodetic data sets. The data record surface motion between March 1996 to May 2000; one represents vertical motion deduced from the leveling observations and the other is the horizontal velocity field deduced from GPS observations. In the inversion, we employed the analytical solutions of surface displacement due to a triangular dislocation element embedded in a homogeneous elastic half space in order to represent the curved plate interface. The vertical data show that the most strongly coupled portion of the subduction interface is concentrated beneath Omaezaki Cape, while the horizontal data show strongest coupling in the shallower region of the subducting plate interface. The estimated maximum value of coupling from the horizontal data is 40 mm/year, while that from vertical data is 25 mm/year. 相似文献