东北近60年盛夏降水特征及其与不同类型厄尔尼诺的联系

为了探讨东北地区盛夏降水的特征及其与不同ENSO的联系,利用1961—2019年国家气象信息中心整编的东北地区204个站日降水资料、NCEP/NCAR逐月再分析资料和国家气候中心ENSO监测结果进行研究分析。结果表明:(1)盛夏降水20世纪90年代到21世纪初进入枯水期,21世纪10年代降水有所增加。1961—2019年降水以5.386 mm/10 a的速率减少,其主要原因是小雨和中雨减少,且近年来降水减少速率变缓;(2)空间上,降水整体呈减少趋势。小雨呈减少趋势,辽宁降水减少最显著,50个站均呈下降趋势,37个站通过显著性检验。中雨和大雨均呈减少趋势,但不显著。暴雨有超过60%的站呈上升趋势,黑龙江以上升趋势为主;(3)厄尔尼诺次年盛夏,中部型(CP型)降水量整体多于东部型(EP型)。EP型辽宁降水偏多,吉林呈西北—东南降水反相分布,内蒙古降水整体偏多,黑龙江整体偏少,且局部地区显著偏少。CP型辽宁降水亦偏多,且多于EP型,吉林为南北反相分布,黑龙江整体偏多,内蒙古整体偏少,且局部显著偏少。由此可以得出,厄尔尼诺可以作为次年东北地区盛夏降水的一个预测因子。

Characteristics of Midsummer Precipitation in Northeast China During the Last 60 Years and Its Relationship with Different Types El Nino Events

Based on the daily precipitation data at 204 meteorological stations within northeast China from National Meteorological Information Centre,ENSO data from National Climate Centre,and monthly reanalysis data provided by the National Centers for Environmental Prediction and the National Center for Atmospheric Research during 1961—2019,characteristics of midsummer precipitation in northeast China during the last 60 years and its relationship with different types El Nino Events were analyzed.The main results are as follows.(1)The midsummer precipitation was more from 1990s to the beginning of the 21st century,after 2010,an ascending precipitation had been seen.The annual precipitation of midsummer decreased at a rate of 5.386 mm/decade from 1961 to 2019,which was mainly due to the decrease of light rain and moderate rain,but the rate of precipitation reduction had slowed in recent years.(2)The spatial distribution of precipitation trend presented decreasing trend.The spatial distribution of light rain trend experienced decreasing trend,while the decreasing precipitation in Liaoning Province was most significant,all stations(50 stations)showed a certain decreasing trend,among which 37 stations showed a significant decreasing trend.Moreover,a certain decreasing trend of moderate rain and heavy rain were showed,however,they were insignificant.The number of stations that showed an increasing trend about storm rain was comparable to the number of those that showed a decreasing trend,a certain increasing trend was showed in Heilongjiang Province.(3)In the following midsummer years of two types El Nino events,the regional precipitation in northeast China was both more than that in the normal years,the CP type was more.In the following midsummer of EP El Nino events,there was anomalously more precipitation in Liaoning Province,the precipitation in Jilin Province presented a dipole-type of‘+-’inverse distribution from northwest to southeast,the precipitation in Inner Mongolia Autonomous Region was anomalously more,the precipitation in Heilongjiang Province was anomalously less,there was significantly less precipitation in partial areas of Heilongjiang Province.To CP El Nino events,there was anomalously more precipitation in Liaoning Province,the precipitation in Jilin Province presented a dipole-type of‘-+’inverse distribution from north to south,the precipitation in Inner Mongolia Autonomous Region was anomalously less,there was significantly less precipitation in partial areas of Inner Mongolia Autonomous Region,the precipitation in Heilongjiang Province was more than that in the normal years.Therefore,El Nino events can be used as one of predictors for the precipitation of the following midsummer in northeast China.