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A three-dimensional spatio-temporal view of major aerosol types over indian region

Hooda, Waris (2021) A three-dimensional spatio-temporal view of major aerosol types over indian region.

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Abstract:Tiny particles suspended in air impact the Earth’s atmosphere in direct and indirect ways; directly in terms of alteration of solar radiation and indirectly by modifying the cloud properties. The aerosols are of both natural and anthropogenic origin. The sources of natural aerosols are pretty much identified, and the transport mechanism is also well understood. However, a large uncertainty is found for anthropogenic aerosols both in terms of source and transport mechanism and is still an area of research. Because aerosols have a shorter atmospheric life, assessing their contribution to climate change is difficult. A complete 3- dimensional spatio-temporal view of aerosols can aid in a better understanding of climatic dynamics and climate change. The Indian region is most suited for such research due to its diversified terrain, high aerosol concentrations, and seasonal fluctuation. The study outlines seasonal and zonal variability along with trends of aerosol vertical distribution over India (which is one of the major aerosol hotspots), in terms of major aerosol types, i.e., dust, polluted dust and smoke. Specific analysis over the selected zones is also reported, along with two special cases, one each for dust and smoke aerosols. To study the three-dimensional spatiotemporal aerosol distribution, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) datasets from 2007 to 2020 are used. Strict screening checks like Aerosol Layer Fraction, Atmospheric Volume Description, etc are applied to the CALIPSO dataset for quality retrieval. The work is supplemented by the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA 2) reanalysis for comparison purposes. In general, higher extinction coefficients are observed to be concentrated close to the ground (above ~1 km). Columnar trends of extinction profiles varied in the different regions, however, in general, found to be increasing in the higher altitudes regime, except during monsoons. The decreasing trend of extinction profiles during the monsoonal period could be primarily related to the decreasing trend of dust aerosols observed in the study area. Meteorological conditions and transit from the Thar Desert or the Arab region have heavily influenced dust dominance in the northern part of the Indian region during monsoon, as evidenced by Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT). During the pre-monsoon and monsoon, polluted dust has increased over the Indian region. An increasing trend of smoke aerosols is seen over the study area during December-February. In particular, changes in aerosol vertical distribution were also studied during the COVID-19 lockdown period of April-May 2020 in the Indian region, wherein a decrease in total extinction profiles has been observed over the majority of the Indian region.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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