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Open AccessArticle

Interdecadal Changes in Aerosol Optical Depth over Pakistan Based on the MERRA-2 Reanalysis Data during 1980–2018

1
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, China
2
Department of Physics, Higher Education, Government of Khyber Pakhtunkhwa, Peshawar 25000, Pakistan
3
Department of Physics, Koneru Lakshmaiah Education Foundation (KLEF), Vaddeswaram, Guntur, Andhra Pradesh 522502, India
4
School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
5
Royal Netherlands Meteorological Institute (KNMI), R & D Satellite Observations, 3731 GA De Bilt, The Netherlands
*
Author to whom correspondence should be addressed.
Academic Editor: Manuel Antón
Remote Sens. 2021, 13(4), 822; https://doi.org/10.3390/rs13040822
Received: 22 December 2020 / Revised: 14 February 2021 / Accepted: 16 February 2021 / Published: 23 February 2021
The spatiotemporal evolution and trends in aerosol optical depth (AOD) over environmentally distinct regions in Pakistan are investigated for the period 1980–2018. The AOD data for this period was obtained from the Modern-era retrospective analysis for research and applications, version 2 (MERRA-2) reanalysis atmospheric products, together with the Moderate-resolution imaging spectroradiometer (MODIS) retrievals. The climatology of AODMERRA-2 is analyzed in three different contexts: the entire study domain (Pakistan), six regions within the domain, and 12 cities chosen from the entire study domain. The time-series analysis of the MODIS and MERRA-2 AOD data shows similar patterns in individual cities. The AOD and its seasonality vary strongly across Pakistan, with the lowest (0.05 ± 0.04) and highest (0.40 ± 0.06) in the autumn and summer seasons over the desert and the coastal regions, respectively. During the study period, the annual AOD trend increased between 0.002 and 0.012 year−1. The increase of AOD is attributed to an increase in population and emissions from natural and/or anthropogenic sources. A general increase in the annual AOD over the central to lower Indus Basin is ascribed to the large contribution of dust particles from the desert. During winter and spring, a significant decrease in the AOD was observed in the northern regions of Pakistan. The MERRA-2 and MODIS trends (2002–2018) were compared, and the results show visible differences between the AOD datasets due to theuseof different versions and collection methods. Overall, the present study provides insight into the regional differences of AOD and its trends with the pronounced seasonal behavior across Pakistan. View Full-Text
Keywords: MERRA-2; MODIS; AOD; driving factors; Pakistan MERRA-2; MODIS; AOD; driving factors; Pakistan
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MDPI and ACS Style

Khan, R.; Kumar, K.R.; Zhao, T.; Ullah, W.; de Leeuw, G. Interdecadal Changes in Aerosol Optical Depth over Pakistan Based on the MERRA-2 Reanalysis Data during 1980–2018. Remote Sens. 2021, 13, 822. https://doi.org/10.3390/rs13040822

AMA Style

Khan R, Kumar KR, Zhao T, Ullah W, de Leeuw G. Interdecadal Changes in Aerosol Optical Depth over Pakistan Based on the MERRA-2 Reanalysis Data during 1980–2018. Remote Sensing. 2021; 13(4):822. https://doi.org/10.3390/rs13040822

Chicago/Turabian Style

Khan, Rehana; Kumar, Kanike R.; Zhao, Tianliang; Ullah, Waheed; de Leeuw, Gerrit. 2021. "Interdecadal Changes in Aerosol Optical Depth over Pakistan Based on the MERRA-2 Reanalysis Data during 1980–2018" Remote Sens. 13, no. 4: 822. https://doi.org/10.3390/rs13040822

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