夏季对流层上空东风带扰动的结构演变特征及其影响西太副高短期东退的机制分析

针对东风带扰动影响西太副高短期异常东退的过程进行了分析。首先给出以下事实:位于西太副高南侧的东风带扰动与西风带扰动接近同经度时,西太副高出现异常东退。10年的统计结果表明,此现象出现的频数很高。挑选典型个例进行合成分析表明:东风带扰动具有垂直尺度深厚,上暖下冷的特征,冷区贯穿对流层中低层;垂直运动与经向风的分布取决于周围环境场;东风带扰动与西风带扰动相向移动到同经度时,南北冷区打通,在纬向上形成暖-冷-暖的温度梯度,从而引发的经向风变化是导致西太副高异常东退的原因。用热力学方程对此温度梯度的形成进行讨论,结果表明,东风带扰动西侧与西风带扰动东侧的变温联接成的负变温带造成了该温度梯度;东风带扰动西侧负变温的形成主要来自温度平流项与绝热加热项的作用;西风槽东侧负变温主要来自绝热加热项与余差项的作用。

The Structure and Variety of the Easterlies Vortex in the Upper Troposphere and the Analysis of the Abnormal Retreat of the Subtropical Anticyclone during Sunmmer

The relationship of the easterlies vortex(EV) and the abnormal retreat of the subtropical anticyclone over the Western Pacific(WPSA) was analyzed.The statistics of ten years showed that this phenomena is frequency.The composite analysis indicated that the EV is deep in vertical and warmer in the upper-troposphere;Vertical movement and meridional wind of EV depends on the environment.When the EV and WV arrives the same longitude,the cooling zones between north and south are linked together,temperature gradient manifested by warm-cold-warm in zonal,which results the change of meridional wind is the cause of WPSA’s retreatment.After the discuss,the studies indicated that temperature changement between north and south generated the temperature gradient;The change in the west of EV depends on temperature advection term and diabatic-heating term while the change in the east of EV depends on diabatic-heating term and remainder term.