1961-2015年海东市降水集中度的变化及月分配特征

Change of Precipitation Concentration Distribution Characteristics and Monthly Distribution of Haidong City from 1961 to 2015

降水的年内变化(月分配和季节变化)对农作物生长、水资源利用及管理具有重要意义,同时也是增暖背景下水循环发生变化的关键过程之一。降水集中指数(PCI,Precipitation Concentration Index)能较好的表征降水的年内集中程度。本文利用海东市5个气象站点1961-2015年的逐月降水观测资料,对海东市的PCI进行了计算分析,研究了PCI的气候特征、变化趋势和降水月分配变化。结果表明,海东市PCI的气候态呈从东南向西北方向逐渐减小,变化趋势自东向西逐渐增加的分布格局;近55年来海东市PCI整体表现为减小趋势,减小速率为0.07/10a;海东市降水集中度的降低主要源于4、7~8、10~11月份MPAP的减少而其他月份MPAP的增加,且其各月降水量变化的线性趋势与MPAP一致,为该地区春末夏初干旱的缓解提供了有利背景但却加大了春初、夏秋季中到末期干旱和夏初涝的可能性。

Seasonal variability of precipitation is an important part of the hydrological cycle,and monthly distribution,of annual precipitation strongly influences agriculture and water resources. The Precipitation Concentration Index（ PCI） is an effective measure of the temporal inhomogeneity of annual precipitation. Using the five weather stations of Haidong City from 1961 to 2015 the monthly rainfall observation data,the calculation analysis was carried out on the eastern city of PCI,the climate characteristics of PCI,change trend and distribution of precipitation in change. The results show that the Haidong City of PCI climate condition was from southeast to northwest gradually decreases,and changing trend gradually increased from east to west of distribution pattern;Haidong City in recent 55 years PCI overall performance for decreasing trend,reduce the rate for a 0. 07/10;Haidong city of precipitation concentration lower stems mainly from 4,7 ~ 8,10 ~ 11 in decreasing MPAP other months MPAP increases,and the linear trend of months precipitation change is consistent with the MPAP,late spring or early summer drought relief for the region provides a good background but increased in the early spring,fall to the end of the possibility of drought and waterlogging early summer.