Abstract:
This study estimates the radiative forcing by biomass burning and dust aerosols over
the Indian subcontinent, with emphasis on the Indo-Gangetic Plains (IGP) during the period from
January 2021 to April 2021, based on multiple satellite and reanalysis datasets. In this respect, we used
retrievals from the Moderate Resolution Spectroradiometer (MODIS) and the Cloud-Aerosol Lidar
and Infrared Pathfinder Satellite Observation (CALIPSO) system, as well as reanalysis data from the
Goddard Earth Observing System, version 5 (GEOS-5), the Modern-Era Retrospective analysis for
Research and Applications, version 2 (MERRA-2), the Copernicus Atmosphere Monitoring Service
(CAMS), and ERA-Interim. According to the MERRA-2 and the CAMS, the highest black carbon (BC)
concentrations in January 2021 were 7–8 µg m−3
, which were significantly lower than measurements
performed in main cities along the IGP, such as Patiala, Delhi, and Kanpur. The meteorological data
analysis accompanied by the CALIPSO lidar measurements showed that the vertical distribution of
total attenuated backscatter (TAB) could reach altitudes of up to ~4–5 km and could be transported
over the central Himalayan region. The spatial-averaged daily aerosol radiative forcing (ARF) values
over the Indian subcontinent from January 2021 to April 2021 were found to range from −51.40 to
−6.08 W m−2
(mean of −22.02 ± 9.19 W m−2
), while on a monthly basis, the ARF values varied
widely, from −146.24 to −1.63 W m−2
(mean of −45.56 ± 22.85 W m−2
) over different parts of the
study region. Furthermore, the spatial-averaged daily BC radiative forcing ranged from −2.23 to
−0.35 (−1.01 ± 0.40 W m−2
), while it varied from −15.29 to −0.31 W m−2
(−2.46 ± 2.32 W m−2
) over
different regions of southern Asia, indicating a rather small contribution to the total aerosol radiative
effect and a large presence of highly scattering aerosols. Our findings highlight the importance of
growing biomass burning, in light of recent climate change and the rapid decline in air quality over
North India and the Indian Ocean.
