Aerosol optical depth (AOD) and Ångström exponent (AE) are observed to be important parameters in understanding the status of ambient aerosol concentration over a particular location and depend not only upon the local but also on the large-scale dynamics of the atmosphere. The present article analyses the AOD and AE parameters retrieved with Moderate Resolution Imaging Spectrometer (MODIS) and Multi-angle Imaging Spectro-Radiometer (MISR) instruments onboard satellites, for the upper (Chamoli) and foothill (Dehradun) regions of Garhwal Himalaya in Uttarakhand, India, from 2006 to 2015. Aerosol properties are investigated at monthly, seasonal, and annual scales. The monthly mean values of MODIS-derived AOD and AE were observed to be 0.18 (± 0.14) and 1.05 (± 0.43) respectively over the Dehradun region. The seasonal maximums in AOD with MODIS and MISR were observed as 0.23 ± 0.06 and 0.29 ± 0.07 respectively in the pre-monsoon season, and the minimum values (0.099 ± 0.02) were observed in the post-monsoon season, over the Dehradun region. In contrast, in the Chamoli region, the maximum AOD (MODIS) was 0.21 ± 0.06 observed in the monsoon season and the minimum was 0.036 ± 0.007 in the post-monsoon season. Over a decade, the AE for Chamoli and Dehradun was found to vary from 0.07 to 0.17 and from 0.14 to 0.20 respectively. The median AE for Chamoli and Dehradun was found to be 1.49 and 1.47 respectively, marking the dominance of fine mode particles of anthropogenic origin. Observations show the presence of dust and polluted dust resulting from the long-range transport from the west. The comparison of AOD values from the two sensors shows a significant correlation (0.73) with slightly higher values from MISR over the year. The results obtained are important in understanding the climatic implications due to the atmospheric aerosols over the abovementioned Himalayan region of Uttarakhand, India.

气溶胶光学深度 (AOD) 和埃斯特罗姆指数 (AE) 被认为是了解特定位置周围气溶胶浓度状态的重要参数，并且不仅取决于局部，还取决于大气的大尺度动态。本文分析了利用卫星上的中分辨率成像光谱仪 (MODIS) 和多角度成像光谱辐射计 (MISR) 仪器检索的北阿坎德邦加瓦尔喜马拉雅山上部 (Chamoli) 和山麓 (Dehradun) 地区的 AOD 和 AE 参数，印度，2006 年至 2015 年。按月度、季节和年度尺度调查气溶胶特性。在德拉敦地区，MODIS 得出的 AOD 和 AE 的月平均值分别为 0.18 (± 0.14) 和 1.05 (± 0.43)。在台拉敦地区，MODIS 和 MISR 的 AOD 季节最大值分别为 0.23 ± 0.06 和 0.29 ± 0.07，出现在季风前季节，最小值 (0.099 ± 0.02) 出现在季风后季节。相比之下，在Chamoli地区，季风季节观测到的最大AOD（MODIS）为0.21±0.06，最小为季风后季节的0.036±0.007。十多年来，Chamoli 和 Dehradun 的 AE 变化范围分别为 0.07 至 0.17 和 0.14 至 0.20。 Chamoli 和 Dehradun 的 AE 中值分别为 1.49 和 1.47，标志着人为来源的精细模式粒子占主导地位。观测表明，存在由西方长距离输送造成的灰尘和污染灰尘。两个传感器的 AOD 值的比较显示，与全年 MISR 的值略有较高存在显着相关性 (0.73)。 获得的结果对于理解上述印度北阿坎德邦喜马拉雅地区大气气溶胶对气候的影响非常重要。