西太平洋暖池对夏季华东海面日最大风速变化的影响

Impact of the Western Pacific Warm Pool anomaly on sea surfacedaily maximumwind speed in Eastern China offshore waters in summer

利用1979—2018年ERA Interim地面10 m风场、位势高度场、温度场和风场,Hadley中心HadISST再分析海温资料,采用SVD分析、合成分析等方法,研究了夏季(6—8月)西太平洋暖池关键海域海表面温度(Sea Surface Temperature,简称SST)对华东海域夏季10 m日最大风速变化的影响关系。SVD分析结果表明,夏季华东近海风速变化与菲律宾以东海域SST有明显负相关,第一模态左、右空间向量的时间系数相关达0.58,通过了置信度为95%的显著性检验。当西太平洋暖池SST正异常时,暖池海域SST增高,西北太平洋副热带高压(以下简称副高)加强,副高脊线北进(西北太平洋副高脊线纬度位置与暖池SST相关系数达到0.46,通过置信度为95%显著性检验)。此时华东近海正处于副高控制,近海下沉运动增强,大气温度垂直剖面有普遍增温现象,10 m风场有偏北风异常,海面风速减小约占40 a平均风速的约30%;当暖池SST负异常时,副高东撤南退,华东近海冷空气活动加强,温度垂直剖面存在显著降温现象,华东近海风速增加占40 a平均风速的20%以上。本研究进一步说明了暖池SST异常是一个有效的预报因子,可用于华东近海海面风速预测预报。

With 10 m wind speed,geopotential height field,temperature,and wind field from ERA-Interim from 1979 to 2018,HadISST reanalyzed Sea Surface Temperature(SST)from the Hadley Center,applying SVD analysis and synthetic analysis methods.We examined the relationship between the Western Pacific Warm Pool SST and the 10 m daily maximum wind speed anomaly in summer(June-August)in Eastern China offshore waters.The SVD analysis results show there is a significant negative correlation between the 10 m wind speed changes in the offshore waters of East China and the SST in the east of the Philippines.The correlation coefficient of the left and right spatial vectors of the first mode is 0.58,which passes the 95%confidence test.When the SST of the Western Pacific Warm Pool is in a positive anomaly year,the SST of the warm pool area increases,the Northwest Pacific Subtropical High(NPSH)strengthens,and the subtropical high ridge usually moves northward,where the correlation coefficient of the latitude of the NPSH ridge and the SST from warm pool reached 0.46,passing the 95%confidence test.At this time,the offshore waters of East China are under the control of the subtropical high,and the sinking motion has increased over the offshore waters,the vertical temperature profile of the troposphere has generally increased,and the 10 m wind shows north wind abnormal over the offshore waters.The reduction of sea surface wind speed has accounted for about 30%of the mean wind speedover the past 40 years.When the warm pool SST is negative,the subtropical high retreats to the southeastward.The activity of cold air in the offshore waters of East China has strengthened.The vertical temperature profile has a significant cooling phenomenon.The increase in wind speed has accounted for more than 20%of the averagewind speed over the past 40 years.This study further demonstrates that the SST anomaly in the warm pool is an effective predictor,which can be used to predict the sea surface wind speed in the offshore waters of Eastern Chinaand to guide economic production and maritime activities in related fields.