西南地区NDVI时空变化及与极端气候事件的关系

Spatiotemporal Change of NDVI and Its Relationship with Extreme Climate Events in Southwestern China

为了研究在全球气候变暖背景下,西南地区归一化植被指数NDVI的时空变化特征及其与极端气候事件的关系,本文基于2000~2019年MODIS植被指数数据、温度和降水日值数据,首先对NDVI的时空变化特征进行了分析,然后对选用的9个极端气候指数与NDVI的相关性进行了讨论。结果表明:1) 西南地区一年四季的植被覆盖度都较高,且四季的植被覆盖度都呈不同程度的上升趋势,其中,夏季的植被覆盖度最高,但增加速率最小,冬季的植被覆盖度最低,春秋季的植被覆盖度相差不大,且春季的增加速率最大;2) 极端气温和极端降水的强度、发生频次和持续时间等都对植被的生长有不同程度的影响作用,其中极端气温对植被生长的影响要高于极端降水,极端暖事件对植被生长有正向作用,极端冷事件对植被生长有负向作用,极端降水对植被生长的影响相对较弱;3) 春夏两季极端暖事件对植被生长有促进作用,而秋冬两季极端冷事件对植被生长有抑制作用。

In order to study the spatio-temporal change characteristics of the normalized vegetation index (NDVI) in the southwestern China and its relationship with extreme climate events under the back-ground of global warming, the spatio-temporal change characteristics of NDVI were firstly analyzed based on MODIS vegetation index data, daily temperature and precipitation data from 2000 to 2019. Then the correlation between NDVI and 9 selected extreme climate indices was discussed. The results showed that: 1) The vegetation coverage in Southwestern China was relatively high throughout the year, and the vegetation coverage in all four seasons showed an upward trend in varying degrees. Among them, the vegetation coverage in summer was the highest, but the increase rate was the smallest, and the vegetation coverage in winter was the lowest. The vegetation coverage in spring and autumn was similar, and the increase rate in spring was the largest;2) The intensity, frequency and duration of extreme temperature and precipitation had different effects on the growth of vegetation. The effect of extreme temperature on the growth of vegetation was higher than that of extreme precipitation. Extreme warm events have a positive effect on vegetation growth, and extreme cold events have a negative effect on vegetation growth. The effect of extreme precipitation on the growth of vegetation was relatively weak;3) The extreme warm events in spring and summer could promote the vegetation growth, while the extreme cold events in autumn and winter could inhibit the vegetation growth.