Abstract
ABSTRACTSurface, column and vertically resolved variations of physical and optical properties of atmospheric aerosol over Hyderabad, a tropical urban location in central India are explored on the basis of ground based and satellite retrieved data. Annual mean aerosol optical depth (τ) observed with Microtops sun-photometer is 0.61 ± 0.07 and seasonally it varied from 0.71 ± 0.06 in pre-monsoon to 0.55 ± 0.05 in winter. Aerosol types are categorized based on Angstrom exponent (α) and τ relations; revealed that the study region is dominated by mixed type (MT) aerosol followed by urban/industrial aerosols under high τ (HUI) category. A consistent diurnal variation of black carbon (BC) is observed irrespective of seasonal variation with annual BC mass concentration is found to be 9.7 ± 1.9 µg m–3. During Telangana Survey day, which was the least pollutant day showed a reduction of 75% BC concentration during day time in comparison to five years average values, indicating the influence of anthropogenic effect over Hyderabad. Vertical information’s on aerosol are analyzed using Cloud Aerosol Lidar Pathfinder Satellite Observations (CALIPSO) and ground based Lidar (LAMP) data. LAMP data analysis shows a significant elevated aerosol layer up to 4 km during pre-monsoon while aerosols are confined below 3 km during post-monsoon and winter. Long term CALIPSO observations revealed that during post-monsoon to winter, the study area is dominated (~60%) by ‘urban’ aerosol; while during pre-monsoon period ~75% of the aerosol type belongs to ‘dusty mix’ category. A decline in short wave flux at the top of the atmosphere (0.66 Wm–2 yr–1) is observed, as revealed by long term Clouds and Earths Radiant Energy System (CERES) data analysis with higher decline rate observed in winter (1 Wm–2 yr–1) followed by pre-monsoon (0.8 Wm–2 yr–1).
Highlights
Aerosols plays an important role in global and regional climate change due to their potential in altering radiation budget by scattering and absorbing incoming solar radiation (Charlson et al, 1992) and to lesser extend outgoing terrestrial radiation
During Telangana Survey day, which was the least pollutant day showed a reduction of 75% black carbon (BC) concentration during day time in comparison to five years average values, indicating the influence of anthropogenic effect over Hyderabad
A decline in short wave flux at the top of the atmosphere (0.66 Wm–2 yr–1) is observed, as revealed by long term Clouds and Earths Radiant Energy System (CERES) data analysis with higher decline rate observed in winter (1 Wm–2 yr–1) followed by pre-monsoon (0.8 Wm–2 yr–1)
Summary
Aerosols plays an important role in global and regional climate change due to their potential in altering radiation budget by scattering and absorbing incoming solar radiation (Charlson et al, 1992) and to lesser extend outgoing terrestrial radiation. Site Description and Data Set Used Aerosol sampling measurements are carried out at the premises of National Remote Sensing Centre (NRSC), situated at the heart of the city, Hyderabad, a fastest growing metropolitan cities in India, with a total area of 650 km. Site Description and Data Set Used Aerosol sampling measurements are carried out at the premises of National Remote Sensing Centre (NRSC), situated at the heart of the city, Hyderabad, a fastest growing metropolitan cities in India, with a total area of 650 km2 It is the capital of newly formed state Telangana, with a population of 4.01 million (Census 2011). The study site is situated on the Deccan plateau at a height of ~557 m above mean sea level It has a hot semi-arid steppe climate with four dominant seasons; winter (Dec–Jan–Feb), pre-monsoon (Mar– Apr–May), monsoon (Jun–Jul–Aug–Sep) and post-monsoon (Oct–Nov).
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