祁连山层状云的时空分布及其环流特征分析  

Temporal and Spatial Distribution of Stratiform Clouds over Qilian Mountains and Circulation Characteristic

作　　者：陈少勇[1,2] 石光普[2] 董安祥[1] 张晓芬[2] 

机构地区：[1]中国气象局兰州干旱气象研究所甘肃省干旱气候变化与减灾重点实验室/中国气象局干旱气候变化与减灾重点开放实验室,甘肃兰州730020 [2]白银市气象局,甘肃白银730900

出　　处：《中国沙漠》2010年第4期946-953,共8页Journal of Desert Research

基　　金：国家自然科学基金重点项目(40533015)资助

摘　　要：利用祁连山区29个测站1961—2001年1—12月云状资料,分析了过去41a祁连山区层状云的时空分布特征及其与大环流变化的关系。结果表明:①祁连山区层状云从西北向东南递增,祁连山主区层状云出现频次高于周边地区。②大部区域层状云显著减少,其中河西走廊东部减少幅度最大。③层状云年平均和季度的年际变化阶段性基本一致,1990年以前以偏多为主,1990年发生突变性减少,以后一直处于偏少的状态。④层状云出现频率与各月降水正相关显著。⑤层状云偏多年与偏少年差值最大的月份是8月和5月,偏多年和偏少年在亚洲500hPa高度场上有明显的差异。⑥与层状云频率显著相关的环流特征量主要有:副高面积、强度、极涡强度、青藏高原高度场指数。祁连山层状云的减少趋势主要是副高面积增大和强度增强的结果。最后,用前期环流特征量为因子建立了祁连山主区层状云频率的预测模型。The temporal and spatial distribution of stratiform clouds over the Qilian Mountains in recent 41 years and its relationship with atmospheric circulation were studied using the cloud data in 1961 2001 obtained from 29 stations in Qilian Mountains. The following results are obtained. （1） The stratiform clouds over the Qilian Mountains increased from northwest to southeast, and the stratiform clouds appeared more frequently over main Qilian Mountain body area than in surrounding areas. （2） Stratiform clouds reduced remarkably in most areas in recent 41 years, especially in east Gansu Corridor. （3） Annual variation of yearly average frequency was basically consistent with the annual variation of seasonal average frequency of stratiform clouds. The frequency of stratiform clouds was relatively high before 1990 and it was relatively low after 1990. （4） The frequency of stratiform clouds was remarkably positive correlative with precipitation of each month. （5） The biggest discrepancy of monthly average frequency of stratiform clouds between the more years and the less years occurred in May and August. The average geo-potential height composites at 500 hPa in the more year and in the less year were different. （6） The main circulation characteristic factors that are remarkable correlative with the frequency of stratiform clouds were area and intensity of subtropical high, intensity of polar vortex, Tibetan Plateau height field index. It was just the enlargement of area and the enhancement of intensity of subtropical high that caused the reduction of frequency of stratiform clouds over Qilian Mountains. Finally, a forecast model of frequency of stratiform clouds in Qilian Mountains was built based on the circulation characteristic factors.

关 键 词：层状云 时空分布 大气环流 预测 祁连山 

分 类 号：P426.5[天文地球—大气科学及气象学]