The contribution of different aerosol types to direct radiative forcing over distinct environments of Pakistan inferred from the AERONET data

Rehana Khan; Kanike Raghavendra Kumar; Tianliang Zhao; Gohar Ali

doi:10.1088/1748-9326/aba2a6

Environmental Research Letters (Jan 2020)

The contribution of different aerosol types to direct radiative forcing over distinct environments of Pakistan inferred from the AERONET data

Rehana Khan,
Kanike Raghavendra Kumar,
Tianliang Zhao,
Gohar Ali

Affiliations

Rehana Khan: ORCiD; Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters, Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), International Joint Laboratory on Climate and Environment Change (ILCEC), Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology , Nanjing 210044, Jiangsu, People’s Republic of China; Department of Physics, Higher Education, Government of Khyber Pakhtunkhwa , Peshawar 25000, Pakistan
Kanike Raghavendra Kumar: ORCiD; Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters, Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), International Joint Laboratory on Climate and Environment Change (ILCEC), Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology , Nanjing 210044, Jiangsu, People’s Republic of China; Department of Physics, Koneru Lakshmaiah Education Foundation (KLEF) , Vaddeswaram, Guntur, Andhra Pradesh 522502, India
Tianliang Zhao: Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters, Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), International Joint Laboratory on Climate and Environment Change (ILCEC), Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology , Nanjing 210044, Jiangsu, People’s Republic of China
Gohar Ali: Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters, Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), International Joint Laboratory on Climate and Environment Change (ILCEC), Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology , Nanjing 210044, Jiangsu, People’s Republic of China; Pakistan Meteorological Department , P.O. Box 44000, Sector H-8/2, Islamabad 45710, Pakistan

DOI: https://doi.org/10.1088/1748-9326/aba2a6
Journal volume & issue: Vol. 15, no. 11
p. 114062

Abstract

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To quantitatively estimate and analyze the contribution of different aerosol types to radiative forcing, we thoroughly investigated their optical and radiative properties using the Aerosol Robotic Network (AERONET) data (2007–2018) over an urban-industrial (Lahore) and coastal (Karachi) cities located in Pakistan. The contribution of inferred aerosol types following the threshold applied for FMF _500 versus SSA _440 and EANG _440−870 versus AANG _440−870 were found the highest for pure dust (PUD, 31.90%) followed by polluted continental (POC, 24.77%) types of aerosols, with moderate contribution was recorded for polluted dust (POD, 20.92%), organic carbon dominating (OCD, 11.85%), black carbon dominating (BCD, 8.77%) and the lowest for the non-absorbing (NOA, 1.79%) aerosol type. Seasonally, the mean (±SD) aerosol optical thickness at 440 nm (AOT _440 ) was found maximum (0.73 ± 0.36) for PUD type in summer and minimum for BCD (0.25 ± 0.04) during spring at Karachi. However, the mean (±SD) AOT _440 varied from 0.85 ± 0.25 during summer to 0.57 ± 0.30 in winter at Lahore, with the highest contributions for POC (29.91%) and BCD (22.58%) and the lowest for NOA (5.85%) type of aerosols. Further, the intensive optical properties showed significant temporal and spectral changes and the complexity of inferred aerosol types over the study sites. The results are well substantiated with the air mass analysis obtained from the concentration weighted trajectory (CWT) model for different aerosol types. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model revealed the strong presence of BCD aerosol type led to a surface (BOA) and top of atmosphere (TOA) forcing of −70.12, −99.78 Wm ^−2 and −9.60, −19.74 Wm ^−2 , with an annual heating rate of 2.10 and 2.54 Kday ^−1 , respectively, at Karachi and Lahore sites.

Published in Environmental Research Letters

ISSN: 1748-9326 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Technology: Environmental technology. Sanitary engineering; Geography. Anthropology. Recreation: Environmental sciences; Science: Physics
Website: https://iopscience.iop.org/journal/1748-9326

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