Publications

Mehta, M; Singh, N; Solanki, R (2019). Changing aerosol loadings over Central Himalayan region (2007-2016) - A satellite perspective. ATMOSPHERIC ENVIRONMENT, 207, 117-128.

Abstract
The paper presents the variation of aerosol columnar variation and vertical profiles over the study area encompassing a portion of Central Himalayan region and the surrounding planar areas. The analysis is carried out using decadal (2007-2016) Level-2 CALIOP (onboard CALIPSO), Level-3 MODIS (onboard Aqua/Terra) and MISR (onboard Terra) datasets. Four seasons have been considered, namely, DJF (December-January-February), MAM (March-April-may), JJA (June-July-August) and SON (September-October-November). The CALIOP data has been screened using quality flags, i.e., CAD score, aerosol layer fraction and extinction quality checks. There are also signatures of elevated aerosol layers, especially during winter (DJF) and post-monsoon (SON) seasons. Latitudinal and longitudinal variations of the vertical structure have also been presented. The HYSPLIT back-trajectory analysis has been carried out in order to explore the changes in the sources of the aerosols during different seasons. It is seen that as we go higher up in the altitudes, the long range transport becomes more dominant. Compared to the other seasons, the air masses are more localized in JJA season. The changing aerosol amounts at different heights of the atmosphere have also been discussed in terms of decadal trends for the four seasons. These trends have been supplemented by the AOD trends from the passive satellite sensors. We find that aerosol amounts have increased in the last decade during DJF and SON seasons, when the atmospheric conditions are more stable. On the contrary, aerosol amounts have significantly decreased in JJA season throughout the vertical column. The effect of changing amounts of aerosols may have impacts on the snow cover variability as well. In this connection, the seasonal trends in snow cover have also been explored during the considered decadal period. Especially during the DJF and SON seasons, decreasing trends in snow cover are observed when the aerosol amounts have been found to be increased.

DOI:
10.1016/j.atmosenv.2019.03.024

ISSN:
1352-2310