夏季中国东部副高北缘雨带强度年际变化成因:副热带西风异常的动力强迫

根据中国东部副高北缘雨带的气候平均位置季节移动情况，定义了雨带强度指数，并用回归分析证实此指数能够很好地描述初夏和盛夏雨带的强度.基于定义的雨带强度指数分析发现，初夏副热带西风对雨带强度影响显著，但盛夏无显著影响.进一步研究表明，初夏副热带西风的增强通过作用于雨带上空西高东低的气温场使得对流层中层暖平流增强，进而加速上升运动，从而增强雨带；而到盛夏，环流形势的季节变化导致暖平流在雨带强度变化中起到的作用减小，这减弱了副热带西风对雨带强度的影响.

Cause of annual variation of the summer rainband intensity along the northern rim of West Pacific subtropical high in eastern China: anomalous force of subtropical westerly wind

Based on the seasonal shift of the climatological-mean rainband along the northern rim of the West Pacific subtropical high, an intensity index for the rainband is defined. Regression analysis confirms that the index can well describe the intensity of the rainband. With the index it is found that the subtropical westerly wind impacts the intensity of the rainband substantially in early summer, but has no obvious effect on the intensity of rainband in midsummer. Further study suggests that in early summer the acceleration of the subtropical westerly wind against the air temperature field, which is low in the east and high in the west, strengthens the warm advection and then the ascent motion over the rainband. Hence the rainband is strengthened. In midsummer, the seasonal shift of the circulation over East Asia weakens the impact of the warm advection on the rainband intensity and the effect of subtropical westerly wind on the rainband intensity as well.