Interannual variations of the atmospheric water vapor content associated with the El Nino event and their impact on the Asian summer monsoon
Toru Terao (1), Takuji Kubota (2)
(1) Faculty of Informatics, Osaka Gakuin University
(2) Graduate School of Science, Kyoto University
We have shown that the variations of the tropical tropospheric temperatures have close relationships with that of the El Nino - Southern Oscillation (Kubota and Terao, 2001). The anomaly of tropical tropospheric temperatures tends to be positive in the summer just after the withdrawal of the El Nino event. In this presentation, the statistical relationships among the variations of the sea surface temperatures, the tropical tropospheric temperatures, the water vapor cycle, and the rainfall patterns are shown.
The magnitude of the warming in the tropics in the upper troposphere is two or three times greater than that in the lower troposphere. The specific humidities in the tropical and subtropical region increase with the warming of the tropical troposphere just after the El Nino event. Unlike the temperature, the magnitude of the humidity variations is smaller in the upper troposphere. However, in the upper troposphere, the correlation with the tropospheric warming is greater than that of the middle troposphere. This may show that the source of the additional water vapor associated with the tropospheric warming is from the outflow of hydrometeors from the deep convections. One of the most prominet feature of the changes associated with the El Nino event appears over the Indian Ocean. All of the sea surface temperatures and atmospheric temperatures and humidities in the lower troposphere rise in the summer after the El Nino event there. The precipitation also tends to increase over the Indian subcontinent and east Asia. In the GAME-IOP year, one of the most typical tropical warming event associated with the strong El Nino appeared. We will also show the result of the case study of this year.
