摘要
20世纪80年代中国学者揭示了印度夏季风与中国华北降水的正相关关系,以后国内外又有一些研究证实了这种正相关关系的存在。文中利用1951—2005年多种气象资料和数值模拟方法,详细讨论了印度夏季风和中国华北地区夏季降水的关系,并针对由印度西北部经青藏高原到中国华北地区形成的正、负、正的遥相关型,从动力因子和热力因子两方面探讨了其中的内在联系,所得结果不但确证了以往的结论,而且进一步揭示了印度夏季风对华北地区降水的影响机制。结果表明:(1)印度夏季风强(弱)时,华北地区容易出现降水偏多(少)的天气;华北地区降水偏多(少)时,印度夏季风偏强(弱)的机率却低一些,这说明印度夏季风的异常变化对华北地区夏季降水有更大的影响。(2)印度夏季风强度主要受印度季风槽的影响,在印度季风槽加深的同时,中高纬的低压槽也加深发展,而这时西太平洋高压脊西伸,来自低纬的西南风水汽输送和源于西太平洋的副热带高压南侧的东南风水汽输送共同作用,有利于华北地区的降水偏多;反之则不利于华北地区的降水。(3)区域气候模式模拟结果也很好地模拟出印度夏季风和华北夏季降水的遥相关关系,其相应的环流异常系统与诊断分析结果非常一致,这从另一方面证实了这种遥相关关系的存在和可靠性。
In the early 1980s, Chinese meteorologists discovered the positive correlation in summer rainfall between India and North China and the correlation was confirmed by some researches at home and abroad. Based on a variety of meteorological data from 1951 to 2005 and numerical simulations, the present study investigates such a correlation between Indian summer monsoon （ISM） and pre- cipitation in North China. Furthermore, we discuss the intrinsic relations of the positive （northwest India）-negative （the Tibetan Plateau）-positive precipitation anomaly （North China） teleconnection pattern from two aspects of thermal and dynamical factors, which not only confirms the precipitation teleconnection previously discovered again, but also reveals the influence mechanism of the ISM on the rainfall in North China. The results show that： （1） when the ISM is strong （weak）, the precipitation in North China tends to be more （less） than normal; however, when the rainfall in North China is more （less） than normal, the probability of the strengthening （weakening） of the ISM is relatively lower. This implies that the ISM anomaly has more impact on the rainfall in North China. （2） The Indian low usually dominantly impacts on the intensity of the ISM. When the Indian low deepens, the low troughs in mid-high latitudes are also frequently strengthened, and the ridge of the western Pacific subtropical high （WPSH） extends westwards. The southwesterly water vapor transport originated from low-latitudes and the southeasterly water vapor transport along the southwestern flank of the WPSH converge in North China, which is favorable for more rainfall there than normal, and vice versa. （3） The simulation results by using of the regional climate model developed by National Climate Center （ReGCM-NCC） also capture the salient feature of the precipitation teleconnection between India and North China. The simulated anomalous atmospheric circulations are approximately the same as diagnosed ones, which confirms the existence and reliability of such a teleconnection from another angle.
出处
《气象学报》
CAS
CSCD
北大核心
2008年第5期789-799,共11页
Acta Meteorologica Sinica
基金
国家重点基础研究发展计划项目"亚洲季风地区水分循环和变异机制"(2006CB403604)
关键词
印度夏季风
华北降水
遥相关
区域气候模式(RegCM—NCC)
Indian summer monsoon, Summer precipitation, North China, Teleeonnection, Regional climate model of the National Climate Center （ReGCM-NCC）
