ACTIONS OF SUMMER MONSOON TROUGHS(RIDGES) AND TROPICAL CYCLONES OVER SOUTH ASIA AND THE MOVING CISK

• 作 者: 李崇银
• 机 构: Institute of Atmospheric Physics, Academia Sinica, Beijing
• 出 处: Science in China,Ser.B
• 发表日期: 1985年11期
• 关键词: monsoon northward tropical convection latitude instability shearing meridional t

The analyzed wind field during MONEX shows that the monsoon troughs (or ridges) over South Asia have 30—50 day oscillation and slowly propagatu northward. Simultaneously, the tropical cyclones in South Asia could disperse energy to the east.Considering the feedback effect of the cumulus convection and the influence of the shearing basic flow, we introduce the vertical shearing basic flow into the conditional instability of the second kind (CISK) model and obtain a moving CISK mode. Under the Summer Monsoon in South Asia, the meridional propagation speed (northward) is about 0.6 latitude per day and the oscillation period is about 34 days for this CISK mode. And it has an easterly group velocity. The above-mentioned characteristics of this mode are similar to the analyzed results of the data during MONEX. Therefore, it can be initially concluded that the CISK mode caused by the shearing basic flow and the feedback effect of the cumulus convection seems to be an important mechanism driving the monsoon tr

The analyzed wind field during MONEX shows that the monsoon troughs (or ridges) over South Asia have a 30-50 day oscillation and a gentle propagatu northward. Simultaneously, the tropical cyclones in South Asia could disperse energy to the east. Considering the feedback effect of the cumulus convection and the influence of the shearing basic flow, we introduce the vertical shearing basic flow into the conditional instability of the second kind (CISK) model and obtain a moving CISK mode. Under the Summer Monsoon in South Asia, the meridional propagation speed ( it has an easterly group velocity. It is about 0.6 latitude per day and the oscillation period is about 34 days for this CISK mode. And it has an easterly group velocity. The above-mentioned characteristics of this mode are similar to the analysis results of the data during MONEX. , it can be initially initially that the CISK mode caused by the shearing basic flow and the feedback effect of the cumulus convection seems to be an important mechanism dri ving the monsoon tr