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991.
内蒙古额济纳旗地貌特征及其构造、气候事件 总被引:3,自引:0,他引:3
根据遥感卫星影像解译及野外地质实地调查,将内蒙古额济纳旗地区的地貌单元划分为中低山区、冲—洪积平原、湖积盆地及风成地貌。根据不同地貌单元组成的沉积物年龄测定和分析,初步认为上新世—早更新世的构造抬升形成苏泊淖尔级湖积阶地;早更新世末(750±60kaBP),发生一次明显的构造抬升活动,形成东、西居延海间的台地;另一次明显的构造抬升记录发生在中更世末—晚更新世初,即149±60kaBP之后,形成黑城冲湖积台地;苏泊淖尔级阶地形成于全新世早、中期,属气候干旱湖泊萎缩形成的气候阶地,阶地沉积物中保存的古风成砂丘,表明晚更新世末—全新世早期气候一度恶化。天鹅湖湖积阶地的形成表明5000a之后一段时间,气候相对适宜;全新世中后期,气候波动强烈,1200aBP出现一次丰水期。 相似文献
992.
In this paper, we summarized the characteristics of tropical cyclones (TC) activity over the western North Pacific in 2004 and analyzed their causation. Compared with the normal, the annual frequency of TC in 2004 was slightly higher, tropical cyclones in 2004 had a longer life span and occurred in a concentrated period, the source of TC were situated eastward; in all tracks of TC, the recurvature tracks took up larger proportion, the landfall regions of TC were located northward, which concentrated from East China to Japan. The primary causes were revealed as follows. Firstly, the intensity and area of the western North Pacific subtropical high was stronger and larger than usual respectively, and its ridge was frequently in the form of cells and stretched northwestward. Secondly, the convergence of intertropical convergence zone (ITCZ) was reinforced and the convergence zone moved more eastward than average. Thirdly, the meridionality of the westerlies was larger than average and the cell-shaped ridge formed a saddle region, which is in favor of TC northward motion and recurature. 相似文献
993.
Numerical experiments on forcing dissipation and heating response of dipole (unipole) are carried out using global spectral models with quasi-geostrophic barotropic vorticity equations. For each experiment model integration is run for 90 days on the condition of three-wave quasi-resonance. The results are given as follows: Under the effects of dipole (unipole) forcing source and basic flow intensity, there exist strong interactions among the three planetary waves and quasi-biweekly and intraseasonal oscillation of the three planetary waves. In the meantime, the changes in the intensity of dipole or unipole forcing source and basic flow have different frequency modulation effects on LFO in the middle and higher latitudes. The results of the stream function field of three quasi-resonant waves evolving with time confirm that the low-frequency oscillation exists in extratropical latitude. 相似文献
994.
995.
Recent Progress in the Impact of the Tibetan Plateau on Climate in China 总被引:14,自引:0,他引:14
Studies of the impacts of the Tibetan Plateau (TP) on climate in China in the last four years are reviewed. It is reported that temperature and precipitation over the TP have increased during recent decades. From satellite data analysis, it is demonstrated that most of the precipitation over the TP is from deep convection clouds. Moreover, the huge TP mechanical forcing and extraordinary elevated thermal forcing impose remarkable impacts upon local circulation and global climate. In winter and spring, stream flow is deflected by a large obstacle and appears as an asymmetric dipole, making East Asia much colder than mid Asia in winter and forming persistent rainfall in late winter and early spring over South China. In late spring, TP heating contributes to the establishment and intensification of the South Asian high and the abrupt seasonal transition of the surrounding circulations. In summer, TP heating in conjunction with the TP air pump cause the deviating stream field to resemble a cyclonic spiral, converging towards and rising over the TP. Therefore, the prominent Asian monsoon climate over East Asia and the dry climate over mid Asia in summer are forced by both TP local forcing and Eurasian continental forcing.
Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast.
On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal (BOB) and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea 相似文献
Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast.
On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal (BOB) and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea 相似文献
996.
1气候概况1.1气温夏季全区平均气温在16.4℃(图里河)~27.0℃(拐子湖)之间,与常年同期平均值相比,全区大部地区偏高到异常偏高,距平在1~4℃之间,其中呼伦贝尔市西部、锡林郭勒盟东北部距平最大为3~4℃。1.2降水夏季全区降水量在20mm(额济纳)~383mm(青龙山)之间,降水主要集中在鄂 相似文献
997.
随着气象事业的快速发展,现代化的气象信息监测系统和天气预报预测分析系统逐步建成,气候观测基础工作正在加强,气象科技创新能力不断加快,气象服务领域进一步拓展,公共气象服务对于包头市经济建设发挥着越来越重要的作用。充分认识公共气象服务的重要性、切实提高气象服务能力 相似文献
998.
2006年冬季(2006年11月1日~2007年2月28日)吉林省总的天气气候特点是:气温特高,降水接近常年。冷空气活动少且强度弱,气温持续偏高;降水时间分布呈前冬(2006年11~12月)少,后冬(2007年1~2月)偏多,空间分布呈东南部山区(吉林、通化、白山)略多,其它市(州)略少的特点。本文简要分析了冬季的天气特点、环流特征及对人民生产生活的影响。 相似文献
999.
第五届全国农运会在江西宜春举办,为保障本届农运会的顺利进行,江西省气象局对气象服务工作进行了周密细致的部署。本文分析了气候条件及气象要素对本届农运会的影响,并从组织管理、开幕式气象保障、数值模式和农运专题网页四个方面分析了本届农运会的气象服务情况。 相似文献
1000.
利用1971~2000年逐月SODA (Simple Ocean Data Assimilation) 同化资料(Carton等,2004)、1980~2000年逐月NCEP/NCAR再分析资料(Kalnay等,1996)探讨中部型(暖海水首先出现在120°W以西)和东部型(暖海水首先出现在120°W以东)El Ni?o事件赤道纬向风应力及洋流的异常变化与暖海水信号的传播特征。研究指出:(1)中部型和东部型El Ni?o事件发生时,太平洋上赤道海表最大西风应力距平在西太平洋地区都有显著的东传现象,但中部型El Ni?o事件西风应力距平强度强,造成西太平洋赤道表层的东向流可达东太平洋地区,这类El Ni?o事件强度偏强。(2)中部型El Ni?o事件,赤道表层洋流辐合区及其下沉运动由西太平洋向东太平洋传播,辐合下沉运动抑制了深层冷海水上翻,西太平洋暖水能够传到东太平洋与西太平洋赤道表层洋流辐合区及其下沉运动的东移有关。(3)东部型El Ni?o事件西太平洋赤道表层洋流辐合区及其下沉运动没能直接传到东太平洋地区,东太平洋暖水形成与局地(120°W以东)辐合下沉运动抑制深层冷海水上翻有关;东部型El Ni?o事件暖池次表层的暖水,不是沿着西太平洋赤道次表层向东传播到东太平洋地区,而是由南太平洋西边界流将暖池海水带到40°S左右的西风漂流区, 再由西风漂流平流到东太平洋。 相似文献