基于MODIS_C061的长三角地区AOD与Angström指数时空变化分析

以长三角为研究区,利用AERONET地基观测的气溶胶光学厚度(AOD)数据,验证了基于MODIS_C061深蓝算法(DB)的AOD产品适用于长三角地区.并利用2000～2018年MOD04_L2产品,分析研究区AOD和Angstr?m指数(AE)的时空变化特征.结果表明,长三角地区AOD呈现东部和北部平原地区高、南部和西部山区低的空间分布,AE呈现南部地区高北部地区低的空间分布. 2003～2007年,AOD年均值增长显著,增长率为23%, 2011年以后逐渐下降; 2001～2003年,AE年均值增长迅速, 2012年以后逐渐下降.AOD在长三角地区呈现夏季最高、冬季最低的显著季节性变化,月均值6月最高达0.84, 8月最低为0.40;AE呈现秋季最高,春季最低的季节性变化,月均值9月最高达1.47, 3月最低为1.08.根据AOD与AE的关系,对长三角地区气溶胶类型进行了研究,结果表明人为产生的城市工业气溶胶是该地区主要的气溶胶类型,其次为混合型和清洁大陆型.

Spatial and Temporal Characteristics of AOD and Angström Exponent in the Yangtze River Delta Based on MODIS_C061

Considering the Yangtze River Delta as the research region, the applicability of the Terra-MODIS C061 deep blue algorithm (DB) AOD products was evaluated using Aerosol Robotic Network (AERONET) ground-based observations. The results demonstrated that the correlation between Terra-MODIS C061 deep blue algorithm (DB) aerosol optical depth (AOD) and AERONET AOD was high (0.95). Characteristics of spatial distribution and temporal variation of AOD and Angström exponent (AE) from 2000 to 2018 in the study area were analyzed using MOD04_L2 products from 2000 to 2018. The results showed that the AOD in the Yangtze River Delta was distributed as "eastern and northern plains high and southern and western mountains low". The AE showed a "northern low and south high" pattern. In terms of temporal distribution, from 2003 to 2007, the annual average AOD increased significantly, with a growth rate of 23%. After 2011, the AOD showed a downward trend. From 2001 to 2003, the annual average of AE rapidly increased, while after 2012, the AE decreased gradually. The AOD showed obvious seasonal changes in the Yangtze River Delta region, with high values in summer and low values in winter. The highest AOD was observed in June (0.84) in all monthly averages, while the lowest was observed in August (0.40). The seasonal average AE was high in autumn and low in spring. The highest AE of 1.47 was observed in September in all monthly averages, and the lowest of 1.08 was observed in March. Aerosol types in the Yangtze River Delta region were investigated according to the relationship between AOD and AE. The results suggested that the urban industrial aerosol was the main aerosol type in the region, followed by mixed type and clean continental aerosols.