华北地区4月降水异常的环流特征及其与海温异常的联系
Atmospheric Circulation Characteristics of Anomalous Precipitation in Northern China in April and Its Relationship to Sea Surface Temperature Anomalies
中文摘要：
利用1960—2007年华北地区81个测站月降水资料和美国NCEP/NCAR再分析等资料，研究了华北地区4月份降水的时空变化特征及其与大气环流异常、关键区海温异常的关系。研究结果表明：在华北地区4月份降水多雨年，北半球中高纬度对流层中高层大气环流呈现出EU遥相关型的负位相，东亚地区上空存在异常反气旋环流，华北地区位于其西南侧，中国东部地区南风强而深厚，从南至北存在强水汽输送带，给华北地区带来较为充沛的水汽；同时，北半球中高纬度地区存在纬向分布的异常大尺度环流和大尺度锋区，华北地区处在异常暖脊和锋区的控制下，冷暖空气交汇、大尺度锋区作用促使该地区降水偏多。而少雨年，北半球中高纬地区大气环流异常以经向型为主，大尺度锋区呈南北分布，华北地区受异常气旋西南部冷平流控制，降水偏少。多雨年华北地区4月份降水与前期或同期海洋关键区域海温异常关系显著，并与海温异常从冬季到春季的演变有较为密切的关系；少雨年与海温异常及其演变的关系不显著，多雨年、少雨年与海洋关键区域海温异常及其演变的关系不对称。
中文关键词：
华北，4月份降水，大气环流异常，海温异常，不对称
KeyWords：
North of China, precipitation in April, anomalous atmospheric circulation, SSTA, asymmetry
Abstract：
Using monthly precipitation data from 81 observational stations in Northern China for 1960-2007 and American NCEP/NCAR reanalysis data, this paper studies temporal and spatial characteristics of precipitation in North of China in April and its relationship to anomalous atmospheric circulation and sea surface temperature anomalies (SSTA) in key oceanic areas. The results show that in rich rainfall years there was negative phase of EU teleconnection pattern in the upper level of troposphere on high latitude in Northern Hemisphere, and East Asia was controlled by and located at southwest of anomalous anticyclone. Accordingly, strong southerly prevailed over Eastern China, and there was strong water vapor transportation from south to north, which brought rich water vapor into North of China. At the same time, at middle and high latitudes were large-scale anomalous zonal circulation and front zone in Northern Hemisphere, and Northern China was controlled by anomalous warm ridge and large-scale front. Meeting of cold and warm air masses, and role of the large-scale front led to rich rainfall in North of China. In less rainfall years at middle and high latitudes were anomalous large-scale meridional circulation and front zone in Northern Hemisphere, and Northern China was affected by cold air flow at southwest of anomalous cyclone and was drought. In rich rainfall years precipitation in Northern China in April had close connections to previous and synchronous SSTA in key oceanic areas, as well as to SSTA evolution from winter to next spring; in less rainfall years, it was not so clear. Therefore, the relationships between rich rainfall and SSTA or its evolution, as well as between less rainfall and SSTA or its evolution, were obviously asymmetric.