基于中国西南地区5个省(市)2001年—2010年期间由中分辨率成像光谱仪MODIS影像资料反演得到的归一化植被指数NDVI产品数据和区内气象站点的连续观测资料,提取了研究区内各气象站点印迹区的NDVI值,计算了降水距平百分率P^a和D指数(降水量与潜在蒸散量之差)这两种气象干旱指数。依据全国植被类型图(2000年版),对研究区内的主要植被类型在季节时间尺度上开展了这两种气象干旱指数与距平NDVI的相关性分析。研究结果表明:距平NDVI对D指数的最大响应滞后约一个月,在此尺度上表现出明显的线性相关性,所选取的6个季度的相关系数均接近或大于0.7,显著性水平小于0.01;对干旱敏感的植被类型如旱地和草地等,表现出更显著的相关性,其相关系数分别达到了0.83和0.71(平均);在干旱季节,D指数与距平NDVI表现出较为一致的空间分异规律,而P^a指数仅在旱情比较严重的情况下或对干旱比较敏感的植被类型区与距平NDVI表现出一致性分布。

Based on the 10-year(2001—2010)time series of Moderate-resolution Imaging Spectroradiometer(MODIS)NormalizedDifference Vegetation Index(NDVI)products and meteorological station data in the area of Southwest China, we extractedthe NDVI values for the footprint of meteorological measurements and calculated the percentage of precipitation anomaly(P^a)and D index(difference between precipitation and potential evapotranspiration)as two drought indices. We then involved the informationon vegetation types(Vegetation type map of China’s landmass, 2000)conducted a compressive spatial-temporal regressionanalyses against these two meteorological drought indices and NDVI anomaly at seasonal time scales. The results showingthat:(1)For most vegetation types, NDVI anomaly signif icantly corresponded to D index with a lag of about one month(R²>=0.7,P<0.01);(2)These correlations were higher for the drought-sensitive vegetation types(i.e. dry land:R²=0.83; grassland:R²=0.71)than other types;(3)The spatial distribution of NDVI anomaly was relatively consistent with that of D index especiallyin drought season while it was only consistent with Pa in very drought season or for drought sensitive vegetation types.