北太平洋中纬度负海温异常对副热带高压影响的数值试验

NUMERICAL EXPERIMENT ON THE INFLUENCES OF MINUS-SSTA OVER MID-LATITUDE NORTHERN PACIFIC ON THE SUBTROPICAL ANTICYCLONE

利用中国科学院大气物理研究所的T42L9全球大气环流模式,研究了1993年夏季北太平洋中纬度海温异常对西太平洋副热带高压的影响。数值试验结果表明:(1)中纬度地区负距平海温异常对其南侧太平洋副热带高压的形态和脊线位置都有影响,负距平海温异常试验的500hPa副热带高压的形态明显比气候平均海温试验更接近于NCEP资料实况,对流层中下层副热带高压脊线的平均位置也比气候平均海温试验要偏南,与实况比也更接近了;(2)在500hPa上,北太平洋中纬度负距平海温异常在其南侧产生的高度扰动使副热带高压向南偏移,而在其北侧产生的高度扰动则沿北太平洋中高纬度、北美中高纬度、北大西洋和欧洲南部以及地中海和北非地区的大圆路径传播,并影响和改变整个北半球大气环流的变化。1993年夏季北太平洋中纬度异常的低海温可能是该年盛夏6、7月北太平洋副热带高压位置异常偏南的重要原因之一。

This study investigates the influences of the minus-SSTA over the northern Pacific Ocean in the mid-latitudes in Summer of 1993 on the subtropical anticyclone by using the T42L9 global circulation spectral model developed by the IAP/CAS. Evidence have the following suggestions. （ 1 ） The pattern of the western Pacific subtropical anticyclone and its ridge location may be affected by the minus-SSTA over the mid-latitude northern Pacific. In the Test of the minus-SSTA, the pattern of the 500 hPa subtropical anticyclone is more similar to the data of NCEP and the ridge of the subtropical anticyclone in the middle-low troposphere is located more southward, which are compared with the Test of the climate SST. （2） The southern disturbances of the minus-SSTA cause the subtropical anticyclone to shift southward, and the northern disturbances propagating along the great circle route affect the changes of Northern Hemisphere general atmospheric circulation. The lower SST on the mid-latitude northern Pacific Ocean in June and July of 1993 may be one of the key factors for the abnormal southern situation of the subtropical anticyclone.