青藏高原冬、春季植被特征及其对西南地区夏季降水的影响

Characteristics of winter and spring vegetation variation over Tibetan plateau and its influence on summer precipitation of southwest China

本文利用西南地区96个气象台站1982—2001年夏季(6—8月)月平均降水资料和归一化植被指数(GIMMS NDVI)资料,分析了青藏高原冬、春季植被特征及其对西南地区夏季降水的影响,得到以下几点认识:青藏高原冬、春季植被呈现东南部覆盖较好,逐渐向西北部减少的特征。近20 a来,高原冬、春季植被总体呈增加趋势,其高原中西部、南部、北部增加明显,而南部侧边界和中东部呈减少趋势。相关分析和奇异值分解表明:高原冬、春季植被对西南地区夏季降水有较明显影响,且这种影响也存在一定的区域差异。高原前期植被变化可以作为西南地区夏季降水长期预报综合考虑的一个参考因子。

On the basis of the monthly precipitation data for the period 1982 -2001 collected from 96 observational stations in Southwest China（ SWC ） and normalized difference vegetation index（ GIMMS NDVI） , the characteristics of vegetation variation over Tibetan plateau（TP） and its influence on summer precipitation in SWC have been analyzed. The result showed that the condition of winter and spring NDVI over eastern and southern arid regions of TP was in a good state but bad in western and northern arid regions. The winter and spring NDVI over TP increased in recent 20 a and displayed a remarkable region difference. These results lead to a conclusion that the growth situation of vegetation over TP may be an important forecasting index which can provide us a new possible clue for SWC rainfall forecasting.