归一化植被指数对陆地水储量和降水变化的响应研究——以塔里木河流域为例

The Response of NDVI to the Changes of Terrestrial Water Storage and Precipitation in Tarim Basin

利用美国国家航空航天局(NASA)提供的MODIS归一化植被指数(NDVI)数据,探讨了2003-2013年10 a间塔里木河流域NDVI的时空动态分布情况,辅以根据GRACE重力场恢复与气候实验重力卫星和TRMM热带降雨测量使命卫星数据所反演的陆地水储量和降水量数据,研究了10 a间塔里木河流域植被覆盖变化对陆地水储量变化的响应。结果表明:(1)春季NDVI最大值为0.033 67,最小值为-0.010 13,夏季NDVI值最大值为0.617 39,最小值为-0.111 72,秋季NDVI最大值为0.563 38,最小值为-0.047 11,冬季NDVI最大值为0.281 61,最小值为-0.078 64;植被NDVI呈现出夏季>秋季>冬季>春季的规律,离河道越近,植被覆盖度也就越高,同时,植被覆盖度指数会随着越靠近沙漠、戈壁而逐步降低。(2)10 a间NDVI呈现大范围的降低趋势,只有少许范围内具有显著的增加趋势;陆地水储量和降水量的变化趋势,从西北向东南方向呈现出由急剧降低逐步递增为急剧增加。(3)区域A、B、C、D 10 a间NDVI的变化趋势分别是较为复杂、微弱降低、微弱增加和非常显著的增加。(4)降水量与NDVI之间呈现正相关关系,但影像有明显的时滞性,降水量与NDVI之间呈现负相关,植被NDVI与陆地水储量呈负相关,但是对NDVI的影响明显比陆地水储量对NDVI的影响更为显著。

By using the normalized difference vegetation index NDVI products provided by the national aeronautics and space administration （NASA） , the distribution of the Tarim River Basin NDVI from January 2003 to January 2013 is discussed and the response of the vegetation changes to land water storage is analyzed according to the GRACE gravity recovery, land water storage and precipitation data inverted with the data from the climate experiment gravity satellite and tropical rainfall measuring mission （TRMM） satellite. Results indicate that the maximum NDVI value in spring is 0.033 67, and the minimum is -0.010 13; the maximum NDVI value in summer is 0.617 39, and the minimum is -0.111 72; the maximum in autumn is 0.563 38, and the minimum is -0.047 11; the maximum in winter is 0.281 61, and the minimum is -0.078 64. The biggest data are always in summer, followed by the data in autumn, winter and spring. Closer to the river, the vegetation coverage is higher, the farther from rivers, or nearer the desert, the vegetation coverage is lower. The NDVI presents a wide range of lower trends in these ten years. Only a small range has a significant increasing trend. Land water storage and precipitation has a sharp decrease in the northwest and a rapid increase in the southeast. The variation trend of region A, B, C and D are respectively relatively co-mplex, slight decrease, slight increase and significant increase. There is a positive correlation between precipitation and NDVI, region C has the biggest positive correlation coefficient, region B has a negative correlation. The influence of precipitation on NDVI has a time lag and it is more obvious than that of land water storage.