用GMS卫星资料反演复杂地形下的降水率   总被引：3，自引：1，他引：3       下载免费PDF全文

陈乾  李兰芳 《水科学进展》1997,8(4):353-358

强降水主要由生命史短的中小尺度天气系统造成,对此类天气系统的预报,目前只有依靠卫星和雷达的实时监测并结合中系统的概念模式外推来完成。由于中国西北地区地形极为复杂,造成雷达盲区,影响其估算降水率。因此采用GMS-4卫星的红外和可见光展宽云图资料,经处理并转换后,再加入相应网格点上的数字化地形高度资料作为因子之一,用多级逐步判别模式估算逐时雨强等级,最后形成一套可在微机上对雨强场进行图像显示及处理的软件系统,满足了现时预报的需要。结果表明,小雨以上的降雨区域不论面积、形状均与实况基本一致。  相似文献   

The onset of Pleistocene glaciation in the Barents Sea: implications for glacial isostatic adjustment     

Georg Kaufmann 《Geophysical Journal International》1997,131(2):281-292

In this paper the effect of a delayed onset of glaciation in the Barents Sea on glacial isostatic adjustment is investigated. The model calculations solve the sea-level equation governing the total mass redistributions associated with the last glaciation cycle on a spherically symmetric, linear, Maxwell viscoelastic earth for two different scenarios for the growth phase of the Barents Sea ice sheet. In the first ice model a linear growing history is used for the Barents Sea ice sheet, which closely relates its development to the build-up of other major Late Pleistocene ice sheets. In the second ice model the accumulation of the Barents Sea ice sheet is restricted to the last 6 ka prior to the last glacial maximum.
The calculations predict relative sea levels, present-day radial velocities, and gravity anomalies for the area formerly covered by the Weichselian ice sheet. The results show that observed relative sea levels in the Barents Sea are appropriate for distinguishing between the different glaciation histories. In particular, present-day observables such as the free-air gravity anomaly over the Barents Sea, and the present-day radial velocities are sensitive to changes in the glaciation history on this scale.
A palaeobathymetry derived from relative sea-level predictions before the last glacial maximum based on the second ice model essentially agrees with a palaeobathymetry derived by Lambeck (1995). The additional emerged areas provide centres for the build-up of an ice sheet and thus support the theory of Hald, Danielsen & Lorentzen (1990) and Mangerud et al. (1992) that the Barents Sea was an essentially marine environment shortly before the last glacial maximum.  相似文献   

Periodicity of magnetic intensities in magnetic anomaly profiles: the Cenozoic of the South Atlantic     

B. D'Argenio  M. Iorio  D. H. Tarling 《Geophysical Journal International》1996,127(1):141-155

Spectral analyses of several published magnetic anomaly profiles from Candé & Kent (1992a) were undertaken prior to analysing, in the same way, raw magnetic anomaly data from similar parts of the South Atlantic. It was found that similar and distinct medium and short wavelengths were present in both the published and raw data. When these are converted into the time domain using the average rate of spreading for each profile, these periodicities appear similar, possibly identical, to those expected from the long-term eccentricity orbital parameters (Fischer, DeBoer & Premoli Silva 1990). While such correlations are not necessarily causative, they suggest that magnetohydro-dynamical processes near the core-mantle boundary may be affected by gravitational changes due to planetary orbital perturbations.  相似文献   

Mechanisms of isostatic compensation of the Zimbabwe and Kaapvaal cratons, the Limpopo Belt and the Mozambique basin   总被引：1，自引：0，他引：1  

O. Gwavava  C. J. Swain  F. Podmore 《Geophysical Journal International》1996,127(3):635-650

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Yucatán karst features and the size of Chicxulub crater     

Martin Connors  Alan R. Hildebrand  Mark Pilkington  Carlos Ortiz-Aleman  Rene E. Chavez  Jaime Urrutia-Fucugauchi  Eduardo Graniel-Castro  Alfredo Camara-Zi  Juan Vasquez  John F. Halpenny 《Geophysical Journal International》1996,127(3):F11-F14

The buried Chicxulub impact structure is marked by a dramatic ring of sinkholes (called cenotes if containing water), and adjacent less prominent partial rings, which have been shown to coincide with maxima in horizontal gravity gradients and a topographic depression. These observations, along with the discreteness and spacing of the features, suggest a formation mechanism involving faulting in the outer slump zone of the crater, which would thus have a diameter of approximately 180 km.
An opposing view, based primarily on the interpretation of gravity data, is that (he crater is much larger than the cenote ring implies. Given the association of the known cenote ring with faults, we here examine northern Yucatan for similar rings in gravity, surface features and elevation, which we might expect to be associated with outer concentric faults in the case of a larger, possibly multiring, structure.
No such outer rings have been found, although definite patterns are seen in the distribution of karst features outside the crater rim. We explain these patterns as resulting mainly from deformation related to the block fault zone that parallels tbe shelf edge of eastern Yucatan.  相似文献   

频率域位场快速正则化反演界面和物性分布     

张贵宾  申宁华 《吉林大学学报(地球科学版)》1996,(4)

从理论与模型算例两方面对一种以Ｐａｒｋｅｒ公式为基础的频率域位场反演方法做了进一步深入研究。表明它是一种能够更有效地引入低通滤波因子的迭代方法。与改进的正则化稳定因子相结合，提出新的快速正则化反演方法。除了将其用于反演求解均质界面以外，它也被推广至变物性的界面反演以及物性反演  相似文献   

云南地区4级地震频度异常特征与强震关系研究   总被引：2，自引：0，他引：2  

王兰兰  刘丽芳 《内陆地震》2004,18(4):359-364

对云南地区18次MS≥6强震事件前中、小地震活动过程进行了分析,发现在这些地震发生前1—3年近场区2°×2°范围内4级地震频度基本上出现了显著增强现象,可以用4级地震年累计频度进行定量描述。通过全时空的扫描,确定年累计频度N≥4为异常阈值,该指标通过了置信度97.5%的R值内符检验。并用调整单元对强震附近4级地震活动增强现象给予了物理解释。  相似文献   

多年冻土地区金刚石矿的环境问题--以Yakutia 西北部Anabar矿为例   总被引：1，自引：0，他引：1  

V.N. Makarov 《冰川冻土》2004,26(Z1):257-262

Placer diamond mining in the Anabar area involves various operations that cause long-term (nearly a quarter of a century) environmental impacts. The long history of mining activities, the technology used to mine the placers, as well as the poor assimilative capacity of the natural systems can result in serious environmental impacts in the area. The primary geochemical processes in the diamond-bearing area are affected by the occurrence of permafrost and relict ice, the lengthy duration of ice cover in water bodies, and the widespread development of cryogenic processes. This promotes physical migration of contaminants, cryogenic metamorphization of waters, and long-term accumulation of organic contaminants in low-temperature, reduction and sedimentation barriers. In this paper, some environmental and geochemical effects of diamond mining in the Arctic area are discussed.  相似文献   

山西省主要河流流域面雨量预报业务流程   总被引：3，自引：1，他引：3  

苗爱梅  郭玉玺  武捷  贾利冬  骆丽楠  刘秀春 《气象》2004,30(9):24-27

以T213、HLAFS模式、MM5中尺度模式输出的格点资料以及日本降水量格点资料为基础，将影响山西降水的天气动力模型归纳为诊断模型，从中引出多个能够全面反映降水模型特征的综合物理因子；根据各种数值模式输出的降水量预报性能和质量优劣特点，依据数值模式的形势场预报优于要素场预报的现实，构造在不同环流形势背景下，启动不同预报方程的面雨量预报业务流程，有效地遏止了在环流形势调整时预报输出不能快速响应的弱点，提高了点和面雨量预报的准确度。  相似文献   

2003年7月上旬张家界特大暴雨山洪分析   总被引：7，自引：4，他引：7  

周雨华  黄培斌  刘兵  张海  黄小玉  丁小剑 《气象》2004,30(10):38-42

对造成 2 0 0 3年 7月 8～ 1 0日张家界特大暴雨山洪的主要影响系统、物理量诊断场资料、多普勒雷达回波资料及自动气象站要素进行了分析 ,并重点分析了张家界特定的地形条件对降水的增幅作用及暴雨的夜发特征 ,为湘西北的暴雨山洪预报提供了一些有益的启示。  相似文献