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新世纪上海地区相对海平面变化影响因素及预测方法 总被引：1，自引：0，他引：1
针对传统相对海平面变化分析方法均将理论海平面变化和地面沉降进行的叠加分析,本文讨论和分析了近20年来全球理论海平面上升速率加快背景下的区域海平面变化速率,利用灰色线性回归组合模型预测上海地区海平面变化趋势。考虑了上海地面沉降发展的新特点,以及长江流域来沙显著减少和河口大型工程建设对上海地区相对海平面变化的影响。在流域来沙量显著减少但来水量变化不大情况下,流域大坝的坝下冲刷使得河槽刷深,河口水位降低,同时长江口深水航道整治工程和促淤围垦工程束狭入海口,使得潮位站水位发生变化,两者的综合效应是目前研究长江口相对海平面变化时必须考虑的重要因素。 相似文献
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C. V. Srinivas R. Venkatesan N. V. Muralidharan Someshwar Das Hari Dass P. Eswara Kumar 《Journal of Earth System Science》2006,115(3):315-332
An operational atmospheric dispersion prediction system is implemented on a cluster supercomputer for Online Emergency Response
at the Kalpakkam nuclear site. This numerical system constitutes a parallel version of a nested grid meso-scale meteorological
model MM5 coupled to a random walk particle dispersion model FLEXPART. The system provides 48-hour forecast of the local weather
and radioactive plume dispersion due to hypothetical airborne releases in a range of 100 km around the site. The parallel
code was implemented on different cluster configurations like distributed and shared memory systems. A 16-node dual Xeon distributed
memory gigabit ethernet cluster has been found sufficient for operational applications. The runtime of a triple nested domain
MM5 is about 4 h for a 24 h forecast. The system had been operated continuously for a few months and results were ported on
the IMSc home page.
Initial and periodic boundary condition data for MM5 are provided by NCMRWF, New Delhi. An alternative source is found to
be NCEP, USA. These two sources provide the input data to the operational models at different spatial and temporal resolutions
using different assimilation methods. A comparative study on the results of forecast is presented using these two data sources
for present operational use. Improvement is noticed in rainfall forecasts that used NCEP data, probably because of its high
spatial and temporal resolution 相似文献
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Flavia Girard Rmy Deschamps Jean‐Franois Ghienne Stphane Rouss Jean‐Loup Rubino 《Sedimentology》2019,66(3):1042-1066
To elucidate the signature of isostatic and eustatic signals during a deglaciation period in pre‐Pleistocene times is made difficult because very little dating can be done, and also because glacial erosion surfaces, subaerial unconformities and subsequent regressive or transgressive marine ravinement surfaces tend to amalgamate or erode the deglacial deposits. How and in what way can the rebound be interpreted from the stratigraphic record? This study proposes to examine deglacial deposits from Late‐Ordovician to Silurian outcrops at the Algeria–Libya border, in order to define the glacio–isostatic rebound and relative sea‐level changes during a deglaciation period. The studied succession developed at the edge and over a positive palaeo‐relief inherited from a prograding proglacial delta that forms a depocentre of glaciogenic deposits. The succession is divided into five subzones, which depend on the topography of this depocentre. Six facies associations were determined: restricted marine (Facies Association 1); tidal channels (Facies Association 2); tidal sand dunes (Facies Association 3); foreshore to upper shoreface (Facies Association 4); lower shoreface (Facies Association 5); and offshore shales (Facies Association 6). Stratigraphic correlations over the subzones support the understanding of the depositional chronology and associated sea‐level changes. Deepest marine domains record a forced regression of 40 m of sea‐level fall resulting from an uplift caused by a glacio‐isostatic rebound that outpaces the early transgression. The rebound is interpreted to result in a multi‐type surface, which is interpreted as a regressive surface of marine erosion in initially marine domains and as a subaerial unconformity surface in an initially subaerial domain. The transgressive deposits have developed above this surface, during the progressive flooding of the palaeo‐relief. Sedimentology and high‐resolution sequence stratigraphy allowed the delineation of a deglacial sequence and associated sea‐level changes curve for the studied succession. Estimates suggest a relatively short (<10 kyr) duration for the glacio‐isostatic uplift and a subsequent longer duration transgression (4 to 5 Myr). 相似文献
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海平面上升对我国沿海低地的影响 总被引：3，自引：0，他引：3
介绍了影响我国沿海低地相对海平面上升的因素,讨论了相对海平面上升对我国海岸侵蚀、沿海低地淹没等影响以及风险等级划分的若干问题。 相似文献
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THE DEPENDENCE OF THE ANNUAL TOTAL ON THE NUMBER OF RAIN‐SPELLS AND THEIR YIELD IN THE MEDITERRANEAN
Rain‐spells are a key parameter for examining the variation in rainfall amounts, especially in arid and semi‐arid areas. A rain‐spell is defined as a period of consecutive days with rainfall above a certain determined Daily Rainfall Threshold (DRT). Two different seasons or two stations may have the same average TOTAL, but different synoptic conditions are the cause for the differences in their Number of Rain‐Spells (NRS) their Rain‐Spells Yield (RSY) or both. The present study examines whether a season is drier/wetter according to its length, or whether it depends on the NRS in 41 Mediterranean stations. It analyses the relationships between dry/wet seasons and various elements of the rain‐spells. These objectives are analysed both at a basin level of the entire Mediterranean, and at a station level. The main conclusions at the basin level are that precipitation amounts are not related to the length of the seasons, and therefore, a Short or a Long season can be either Dry or Wet. The significant positive correlation between the TOTAL and the annual NRS that was found indicates that a Dry season tends to have Few rain‐spells and a Wet season tends to have Many rain‐spells. At the station level of most stations, a Dry or Wet season is caused mainly by changes in the RSY and less so by changes in the NRS. This tendency is more evident in the southern Mediterranean. Furthermore, Wet seasons are characterized by an increase in the number of Long rain‐spells (longer than three days) and mainly in the RSY of these spells. These conclusions may serve to characterize the rainfall regime under any scenario due to a climatic change. 相似文献
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