REGIONAL AND TEMPORAL VARIATIONS IN PRECIPITATION IN THE EASTERN PART OF THE HIMALAYAS

本研究的目的是阐明喜马拉雅东部降水的季节内变化的区域特征及其与印度夏季风的关系。主要对不丹喜马拉雅地区的日降水进行分析，结果如下：1。不丹喜马拉雅南麓和山内盆地的降水差异主要取决于日降水强度，降水强度差异被认为与两种不同空间尺度的空气环流系统有关。一个是天气尺度上的季风环流系统，另一个是局地尺度上的山谷环流系统。在6月和7月印度夏季风的间歇期（活跃期），不丹和尼泊尔喜马拉雅地区的降水被认为是增加（减少）的。然而，从8月中旬开始，不丹和尼泊尔喜马拉雅地区降水与夏季风活动的关系并不明确。1989年暴雨的原因是5月18日和6月15日前后经过不丹喜马拉雅附近的气旋。气旋在不丹喜马拉雅地区带来了相对广泛的暴雨，在山内盆地，他们有很多降水。结果表明，印度夏季风活动与喜马拉雅地区降水的关系在7 ~ 8月发生了变化。此外，它应该小心气旋造成的损害，特别是在不丹喜马拉雅山脉的山内盆地。

The purpose of this study is to clarify the regional characteristics of intraseasonal variation in precipitation in the eastern part of the Himalayas and its relationship with the Indian summer monsoon. The daily precipitation is analyzed mainly in the Bhutan Himalaya and the results are as follows ;1.The difference in precipitation between the southern foothills and the intramontane basin in the Bhutan Himalaya depends mainly on the intensity of daily precipitation, and the difference in the intensity of precipitation is considered to be related to two air circulation systems with a different spatial scale. One is the monsoon circulation system on a synoptic scale and the other is the mountain and valley circulation system on a local scale.2.The precipitation in the Bhutan and Nepal Himalayas is considered to increase (decrease) during the break (active) phase of the Indian summer monsoon in June and July. However, from mid August, the relationship between precipitation in the Bhutan and Nepal Himalayas and the activity of summer monsoon is not clear.3.The cause of heavy rains in 1989 is the cyclones passing near the Bhutan Himalaya around 18th May and 15th June. The cyclone brings relatively widespread heavy rains in the Bhutan Himalaya and, in the intramontane basin, they have much precipitation.Based on above results, it is shown that the relationship between the activity of Indian summer monsoon and the precipitation in the Himalayas changes from July to August. Moreover, it should be careful of the damages caused by the cyclone, especially in the intramontane basin of the Bhutan Himalaya.