基于MODIS数据的中国气溶胶光学厚度时空分布特征

Spatio-temporal distribution characteristics of aerosol optical depths in China based on MODIS data

利用Aqua/MODIS C006大气气溶胶光学厚度(AOD)遥感数据,统计了中国2007—2017年的AOD值,对11年间AOD的空间分布特征及年际和四季变化特征进行分析,并采用Theil-Sen Median趋势分析、标准偏差和Hurst指数3种方法,分析了基于像元的中国大陆地区AOD时空变化特征.结果表明:①空间特征:11年间AOD分布具有东部高、西部低,东部减少、西部基本不变的特征;②时间特征:AOD变化在年际间呈余弦曲线式波动下降的特征,最高值出现在2007年,为0.34,最低值出现在2016年,为0.22,11年间AOD平均值下降了35.29%;年内AOD值表现出春夏高(0.33/0.32),秋季次之(0.26),冬季最小(0.15)的季节变化特征;③稳定性与持续性:东部稳定性差但集聚、西部稳定性好但分散,东西差异显著;中国AOD持续性特征以弱反持续性为主,弱持续和弱反持续镶嵌分布,西北干旱区表现为强反持续性的特点.

The Aqua/MODIS C006 aerosol optical depths （AOD） products were used to calculate the AOD values in China from 2007 to 2017. The spatial distribution characteristics of AOD over the 11 years as well as the characteristics of inter-annual and seasons changes were analyzed. In addition, the spatial and temporal changes were analyzed using the Theil-Sen Median trend analysis, standard deviation and Hurst index based on pixels of AOD in China's Mainland. The results show that： ① Spatial characteristics ： the distribution of AOD over the 11 years demonstrates the characteristics of high in the east, low in the west, decreasing in the east, and basically unchanged in the west; ②Temporal characteristics： the variation of AOD shows a cosine curve-like fluctuation decline from year to year. The highest value appeared in 2007 was 0.34 and the lowest value appeared in 2016 was 0.22, with a decrease of 35.29% comparatively. In one year, the seasonal variation was characterized by spring-summer （0.33 / 0.32）, autumn （0.26） and winter （0.15） ; ③ Stability and persistence： the stability in eastern China was poor but concentrated, while the stability in western China was good but scattered, with the significant difference between the East and the West. The persistent feature of AOD in China is mainly weak anti-persistence, weak persistent and weak anti-persistence mosaic distribution, but strong anti-persistence is the main characteristic in arid areas of northwest China.