热带印度洋持续暖海温对东亚初夏大气环流影响的数值研究

NUMERICAL STUDY OF THE EFFECTS OF PERSISTENT WARMER SEA SURFACE TEMPERATURE FOR TROPICAL INDIAN OCEAN ON ATMOSPHERIC CIRCULATION IN THE EARLY SUMMER IN EAST ASIA IN 1991

用改进的CCM1(R15L12)气候模式,模拟研究了1991年热带印度洋持续暖海温对东亚初夏季节大气环流的影响。结果表明,热带印度洋海温持续偏暖有利于初夏高原上空大气增温,从而有利于热带东风急流的发展北移和东亚南支西风急流的北跳,并引起5月份西太平洋副热带高压明显加强北抬。印度洋暖海温还引起初夏东亚大陆温度场回升,对南半球越赤道气流发展和南海夏季风的加强起到积极作用。上述特征加速了东亚初夏季节转换过程,有利于江淮梅雨较早发生。

By employing the CCM1(R15L12)long-rang spectral model, study is undertaken of the effects of sea surface temperature anomaly(SSTA) for tropical Indian ocean on circulation transformation in the early summer in East Asia in 1991. The results indicate that warmer SSTA contributes to the increasing of the temperature over the Plateau in early summer, resulting in the intensification of tropical easterly jet on 100 hPa and northward shift of Northern Hemisphere subtropical westerly jet in May. It is obviously favorable for the subtropical high enhancement over western Pacific Ocean in May and subtropical westerly jet maintaining at 35～40 N in June, making the Mei-Yu come earlier and stay over the Changjiang basin in 1991. Furthermore, warmer SSTA is also advantageous to averaged temperature rise in East Asia land region and Nanhai monsoon development. These roles are helpful in accelerating the seasonal transition for East Asia in early summer.