华北地区春季降水与ENSO的关系

Relationship Between the Spring Precipitation in North China and ENSO

根据1961—2010年华北地区53个气象站降水资料、NOAA海温资料及NCEP/NCAR再分析资料,采用相关分析和合成分析等统计方法,研究了华北地区春季降水与ENSO的关系。结果表明,华北地区春季降水偏少年份出现的频次高于偏多年份,强度强于偏多年份的,并且呈现出阶段性偏多和偏少特征,尤其是在20世纪70年代呈现出比较突出的偏少特征,一直延续到80年代中期。华北春季降水和前冬Nino3区海温存在显著的正相关关系(相关系数达0.42):当前冬Nino3区海温负异常时,华北春季降水偏少;而正异常时,华北春季降水偏多。因此,前冬海温异常对华北春季降水有较好的指示意义。大气对前冬海温的异常有明显的响应:Nino3区海温正异常可导致次年春季热带和西北太平洋副热带地区的500 h Pa高度场升高(即西太平洋副热带高压偏强、偏西、偏北),东亚大槽偏弱、偏东,巴尔喀什湖至贝加尔湖的高度场降低(即该地区经常有低槽维持),亚洲至西太平洋地区盛行纬向环流;而前冬Nino3区海温负异常则相反。

According to the NOAA SST, NCEP/NCAR reanalysis data and spring precipitation data of 53 stations in North China from 1961 to 2010, the paper analyzed relationship of the spring precipitation in North China and ENSO by using the statistical methods of correlation analysis and synthesis analysis. The results show that the frequency of negative precipitation anomaly is more than that of positive precipitation anomaly, and the intensity of negative precipitation anomaly is stronger than that of positive precipitation anomaly. The spring precipitation in North China displays the periodical characteristic of negative and positive precipitation anomaly. Especially in the 1970＇s, the negative precipitation anomaly is very prominent and continues until the middle of 1980＇ s. The correlation of the spring precipitation in North China and the pre-winter SST of the Nino3 region is significant positive （ correlation coefficient is 0.42）. Composting the spatial distribution of spring precipitation in North China region during the time period of the positive and negative anomalies pre-winter Nino3 respectively, when the pre-winter SST of the Nino3 region is negative, the spring precipitation in North China is negative. On the contrary, when the pre-winter SST of the Nino3 region is positive, the spring precipitation in North China is positive. The pre-winter SST anomaly has good instruction significance for spring precipitation in North China. The atmosphere has significant response to the pre-winter SST anomaly. The positive anomaly of the pre-winter Nino3 SST can lead to 500 hPa height field increasing over the tropical and northwest Pacific subtropical region. Specifically, the intensity of the west Pacific subtropical high is stronger. The western extending ridge point of the west Pacific subtropical high is by west. The position of the west Pacific subtropical high is by north. The intensity of East Asian trough is weaker and position of it is by east. The height of the field from the Balkhash Lake to Lake Baikal is reduced, namely the region often has low trough maintaining. The region from the Asia to the western Pacific region prevail zonal circulation. When the prewinter Nino3 SST region is negative, the corresponding 500 hPa height field is opposite.