赤道印度洋海温偶极子的气候影响及数值模拟研究

在分析研究印度洋海温变化的基本特征,尤其是在分析赤道印度洋海温偶极子及其影响的基础上,利用IAP9L大气环流模式模拟研究了赤道印度洋海温偶极子异常对亚洲季风区气候变化的影响.其结果表明,印度洋、亚洲南部和东部地区的流场和降水都对印度洋海温异常的强迫作用比较敏感.正位相印度洋偶极子的作用使得赤道东印度洋-印度次大陆南部-阿拉伯海一带出现距平东风,孟加拉湾-中南半岛出现异常反气旋性环流,从而对减少印度南部和中南半岛南部、印度尼西亚地区的夏季降水,以及增加中国南部和东非的夏季降水有十分重要的作用.与此相反,负位相印度洋偶极子的作用将使赤道东印度洋附近出现西风异常,孟加拉湾-中南半岛存在异常气旋性环流,从而使印度次大陆和中南半岛南部、印度尼西亚地区的降水增加,使中国西部和孟加拉湾的降水减少.数值模拟结果与资料分析相互映证,切实地揭示了印度洋海温偶极子对亚洲季风区的气候变化有重要影响.

Numerical simulations on the climate impacts of temperature dipole in the equatorial Indian Ocean

Based on the analyses of fundamental feature of sea surface temperature variation in the Indian Ocean,particularly on the dipole in the equatorial Indian Ocean(IOD) and its influences,the impacts of the IOD on the Asian monsoon climate variation is studied by using numerical simulation with a GCM(IAP9L).The results show that the atmospheric circulation and precipitation over the Indian Ocean,South Asia and East Asia are quite sensitive to the forcing of anomalous SST in the equatorial Indian Ocean.The positive phase of the IOD will lead to anomalous easterly wind over the equatorial eastern Indian Ocean-southern Indian Peninsula the Arabian Sea,and anomalous anticyclonic circulation over the Bay of Bengal-China/Indian Peninsula.Thus it plays an important role in decreasing summer rainfall in the Indian Peninsula,South part of China/Indian Peninsula and Indonesia area,and increasing summer rainfall in southern China and East Africa.The negative phase of the IOD will lead to anomalous westerly wind over the equatorial eastern Indian Ocean and anomalous cyclonic circulation over the Bay of Bengal-China/Indian Peninsula.Thus it plays an important role in increasing summer rainfall in the Indian Peninsula,south part of China/Indian Peninsula and Indonesia area,and decreasing summer rainfall in southern China,the Bay of Bengal and East Africa.The simulation results in this paper are similar with that in the data analyses,the important impact of the IOD on climate variation in Asian monsoon area has been exposed practically.