江西省降水与不同时空尺度下植被NDVI关系研究

Relationships between Precipitation and Different Spatio-temporal Vegetation NDVI in Jiangxi Province

利用NASA/AVHRR的982—2006年NDVI(Normalized Difference Vegetation Index)数据和江西省79个气象站1982—2005年逐日降水观测资料,分析了江西省植被和降水的时空变化特征以及年降水和不同时空尺度的植被NDVI间相关关系。结果发现:1)降水在季节和年尺度上变化均不明显;年植被NDVI未发生显著变化,春季植被NDVI呈显著上升趋势,夏、冬两季呈显著下降趋势。2)当植被NDVI的空间尺度达到9×9(即36 km×36 km,可称为"最优时空尺度")时,二者相关系数基本稳定,说明年降水和该空间尺度植被的关系能较好地反映出降水与植被的相互关系。3)各季节降水与不同时空尺度下植被NDVI关系表现为除秋季外,其他3个季节的降水均与植被NDVI显著相关,但与之对应的植被NDVI"最优时空尺度"不尽相同。因此,考虑到不同时空尺度的植被NDVI与降水之间关系存在较大差异,在今后研究二者之间关系时,必须充分考虑时空尺度对研究可能带来的不确定性。

Using 15-day NASA/AVHRR NDVI（Normalized Difference Vegetation Index）datasets and daily precipitation data from79 weather stations in Jiangxi Province,spatio-temporal characteristics of their changes were analyzed in this current study. For the whole province,precipitation with both yearly and seasonal scales presented no significant change. Despite of no significant decrease for annual NDVI,the significant increases of NDVI was found in spring,while decreases in summer and winter. Comparing the correlation coefficients of annual precipitation with NDVI on different spatio-temporal scales,the coefficient peaked on the scale of9 grid ×9 grid（also 36 km×36 km;called as the ＂optimum spatio-temporal scale＂）,and then basically remained steady which suggested that annual precipitation and NDVI existed a strongest linkage on the scale. In addition,the correlations between seasonal precipitation and different spatio-temporal NDVI had also been investigated. Seasonal precipitation closely linked to NDVI with the different ＂optimum spatio-temporal scales＂except in autumn. To sum up,based on the impacts of the difference spatio-temporal scales,the uncertainty of the relationship between NDVI and precipitation needed further researches.