摘要
We partition the observed wind field into rotational and divergent wind fields to analyze the stream field of Ty- phoon Polly (No.9216),which landed on 31 August 1992 and caused severe weather and large damage in the eastern China.The results indicate that the preservation of typhoon intensity after landing and the heavy rainfall took place on the northern periphery of typhoon are due to the strong divergent winds on the regions of low level jet (LLJ) and high level jet (HLJ) around the typhoon.The direction of divergent winds in the LLJ is perpendicular to the observed wind. But,the direction of divergent winds around the HLJ axis is parallel to the observed winds.The stream function and the rotational wind corresponding to the horizontal vorticity display the vertical circulation associated with the heavy rain, which is stronger than the vertical circulation around the typhoon center.The three-dimensional trajectories exhibit the warm and moist air parcels of LLJ traveling northward into the heavy rainfall region and ascending,then turning eastward in the HLJ.
We partition the observed wind field into rotational and divergent wind fields to analyze the stream field of Ty- phoon Polly (No.9216),which landed on 31 August 1992 and caused severe weather and large damage in the eastern China.The results indicate that the preservation of typhoon intensity after landing and the heavy rainfall took place on the northern periphery of typhoon are due to the strong divergent winds on the regions of low level jet (LLJ) and high level jet (HLJ) around the typhoon.The direction of divergent winds in the LLJ is perpendicular to the observed wind. But,the direction of divergent winds around the HLJ axis is parallel to the observed winds.The stream function and the rotational wind corresponding to the horizontal vorticity display the vertical circulation associated with the heavy rain, which is stronger than the vertical circulation around the typhoon center.The three-dimensional trajectories exhibit the warm and moist air parcels of LLJ traveling northward into the heavy rainfall region and ascending,then turning eastward in the HLJ.
基金
This study is supported by the National Natural Science Foundation of China under the program No.49335062
