All records show the characteristics of high precipitation and large swing before 1100aad , but the characteristics of low precipitation and small swing after 1100aad . during the medieval warm period there is a very dry period 相同时段氧同位素与纹层厚度、灰度对比表明，过去2000多年主要是暖湿、干冷的气候组合方式，但在气候转型期温度、降水并没有完全表现同步变化，体现干暖、冷湿组合。
The findings show that there exists overlap between macroscale convergence and warm advection if the degree of clock - wise turn dosen " t keep constant on both sides of zero doppler velocity contour about the near range of the observational site . the overlap produces vertical vapor transport and upward convergence movement favorable for formation and continuation of rain gush 结果表明：零速度带在测站近距离两侧的弯曲程度不一致是暖平流与大尺度辐合运动的迭加所造成，这一结构为暴雨产生和维持提供了有利的水汽垂直输送和辐合上升运动。
