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排序方式: 共有104条查询结果,搜索用时 15 毫秒
1.
The Northward Shift of Climatic Belts in China During the Last 50 Years and the Corresponding Seasonal Responses 总被引:29,自引:0,他引:29
Along the meridian of 105°E, the Chinese region are divided into two parts, east and west. The results show that in the east part of China the temperate extratropical belt, the warm extratropical belt,and the northern subtropical belt shift northward significantly, whereas the middle subtropical belt and the southern subtropical belt have less or no change. As for the northern subtropical belt, the maximal northward shift can reach 3.7 degrees of latitude. As for the warm extratropical belt, along the meridian of 120°-125°E, the maximal northward shift can reach 3-4 degrees. In the west part of China, each climatic belt changes little. Only in the Xinjiang area are the significant northward shifts. Correspondingly, it is found that in the last 50 years the traditional seasons have changed. For Beijing, Hailar, and Lanzhou, in general, summer becomes longer and winter shorter over the last 50 years. Summer begins early and ends late with respect to early 1950s. Contrary to the summer, winter begins la 相似文献
2.
该文首先采用合成分析的方法研究了江淮入梅前后大尺度大气环流的演变特征和西太平洋副热带高压西伸北跳的可能机制。研究结果表明, 江淮入梅前期的最显著的特征是:副热带高压首先在太平洋中部增强北跳, 而后向西扩展导致太平洋副高西部脊 (120°E) 的增强北跳。进一步分析表明, 在太平洋中部副热带高压的增强北跳和西伸之前, 副热带高压南侧ITCZ中对流和孟加拉湾北部的对流活动明显并且都经历了一次增强活跃过程, 这意味着热带ITCZ和孟加拉湾北部对流的异常活跃可能对副热带高压的增强北跳西伸产生影响。全球大气环流模式模拟结果表明, 赤道中太平洋ITCZ中对流异常活跃不仅可导致副热带高压的增强北移, 而且还可导致副热带高压西伸, 与诊断分析结果相一致。 相似文献
3.
Large tectonic movement of the Japan Arc in late Cenozoic times inferred from paleomagnetism: Review and synthesis 总被引:4,自引:0,他引:4
Abstract Paleomagnetic studies facilitate an understanding of the evolution of the Japan Arc in Cenozoic times from the perspective of tectonic movement. The Japan Arc rifted from the Asian continent in the middle Miocene, while East Asia, including the Japan Arc, moved northward at the same time. The rifting phenomenon of the Japan Arc is described by differential rotation of Southwest and Northeast Japan. Southwest Japan was rotated clockwise through about 45° and Northeast Japan was rotated counter-clockwise through about 40°. This differential rotation occurred concurrently at about 15 Ma. Eighty percent of the rotation was completed during a period of 1.8 million years. These factors lead us to propose a'double door'opening mode with a fast spreading rate of 21 cm/yr for the evolution of the Japan Sea, suggesting that the asthenosphere with a low viscosity was injected beneath the Japan Sea area. The large northward motion of East Asia in relation to Europe is expected from the apparent polar wander path constructed from the paleomagnetic data of the Japan Arc. East Asia may have moved northward by more than 1700 km between 20 Ma and 10 Ma accompanied by a slightly clockwise rotation of 10°. The eastern part of the Eurasian plate was subjected to extreme geodynamic conditions in late Cenozoic times. 相似文献
4.
吴锡生 《吉林大学学报(地球科学版)》1992,(3)
本文应用RESMA系统对区域化探金异常进行了筛选评价,并对筛选出的异常应用二维地球化学剖面延拓推测其深部的含矿性及预测其远景储量. 相似文献
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6.
地幔对流及其对地壳表层拉张盆地的影响 总被引:4,自引:0,他引:4
回顾近十年来在地幔对流方面的最新研究进展,阐述了板块俯冲后在地幔中的演化特征,以及地幔上升流即地幔柱的驱动机制和地质效应。特别介绍了地幔柱对地壳表层拉张盆地形成和充填过程的影响。进一步探讨了地幔柱活动在济阳坳陷的地质表现及其引发的火山岩浆活动、碎屑充填特征。认为盆地演化的阶段性间接反映了地幔对流的阶段性。 相似文献
7.
登陆北上台风暴雨突发性增强的一种机制研究 总被引:6,自引:1,他引:5
采用一个三维混合模式对1992年8月30日至9月2日一次登陆北上台风暴雨过程进行了模拟。模式可以较准确地预报出与地面倒槽相一致的地面降水位置及降水量值。模拟的台风云系结构与卫星云图比较表明,外围云场与实例云况吻合很好,验证了本模式模拟卫星云图的能力,对卫星云图预报有实际意义;暴雨突然增幅的直接原因是高层冰云与低层供水云的突然北移重叠造成的。受地面倒槽附近强烈辐合抬升的动力作用,各相态云系的分布与垂直运动紧密相关;辐合线右侧的东南低空急流为降水的增幅及维持提供水汽来源;云的相变潜热非绝热加热作用对暴雨的增幅及维持具有正反馈作用,它对暴雨维持具有积极贡献。 相似文献
8.
9.
Northward propagation in summer and eastward propagation in winter are two distinguished features of tropical intraseasonal oscillation(TISO) over the equatorial Indian Ocean.According to numerical modeling results,under a global warming scenario,both propagations were intensified.The enhanced northward propagation in summer can be attributed to the enhanced atmosphere-ocean interaction and the strengthened mean southerly wind;and the intensified eastward propagation in winter is associated with the enhanced convection-wind coupling process and the strengthened equatorial Kevin wave.Future changes of TISO propagations need to be explored in more climate models. 相似文献
10.
The tropical intraseasonal oscillation in SAMIL coupled and uncoupled general circulation models 总被引:4,自引:1,他引:3
Simulations of tropical intraseasonal oscillation(TISO) in SAMIL,the Spectral Atmospheric Model from the Institute of Atmospheric Physics(IAP) State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) coupled and uncoupled general circulation models were comprehensively evaluated in this study.Compared to the uncoupled model,the atmosphere-ocean coupled model improved the TISO simulation in the following aspects:(1) the spectral intensity for the 30-80-day peak eastward periods was more realistic;(2) the eastward propagation signals over western Pacific were stronger;and(3) the variance distribution and stronger signals of Kelvin waves and mixed Rossby gravity waves were more realistic.Better performance in the coupled run was assumed to be associated with a better mean state and a more realistic relationship between precipitation and SST.In both the coupled and uncoupled runs,the unrealistic simulation of the eastward propagation over the equatorial Indian Ocean might have been associated with the biases of the precipitation mean state over the Indian Ocean,and the unrealistic split of maximum TISO precipitation variance over the Pacific might have corresponded to the exaggeration of the double Intertropical Convergence Zone(ITCZ) structure in precipitation mean state.However,whether a better mean state leads to better TISO activity remains questionable.Notably,the northward propagation over the Indian Ocean during summer was not improved in the mean lead-lag correlation analysis,but case studies have shown some strong cases to yield remarkably realistic northward propagation in coupled runs. 相似文献