Abstract. Measurements of the vertical profiles of the optical properties (namely the extinction coefficient and scattering and absorption coefficients respectively σext ∕ σscat ∕ σabs) of aerosols have been made across the Indo-Gangetic Plain (IGP) using an instrumented aircraft operated from three base stations – Jodhpur (JDR), representing the semi-arid western IGP; Varanasi (VNS), the central IGP characterized by significant anthropogenic activities; and the industrialized coastal location in the eastern end of the IGP (Bhubaneswar, BBR) – just prior to the onset of the Indian summer monsoon. The vertical profiles depicted region-specific absorption characteristics, while the scattering characteristics remained fairly uniform across the region, leading to a west–east gradient in the vertical structure of single-scattering albedo (SSA). Integrated from near the ground to 3 km, the highest absorption coefficient and hence the lowest SSA occurred in the central IGP (Varanasi). Size distribution, inferred from the spectral variation of the scattering coefficient, showed a gradual shift from coarse-particle dominance in the western IGP to strong accumulation dominance in the eastern coast with the central IGP coming in between, arising from a change in the aerosol type from a predominantly natural (dust and sea salt) type in the western IGP to a highly anthropogenic type (industrial emissions, fossil fuel and biomass combustion) in the eastern IGP, with the central IGP exhibiting a mixture of both. Aerosol-induced short-wave radiative forcing, estimated using altitude-resolved SSA information, revealed significant atmospheric warming in the central IGP, while a top-of-atmosphere cooling is seen, in general, in the IGP. Atmospheric heating rate profiles, estimated using altitude-resolved SSA and column-averaged SSA, revealed considerable underestimation in the latter case, emphasizing the importance and necessity of having altitude-resolved SSA information as against a single value for the entire column.
<p><strong>Abstract.</strong> Measurements of the vertical profiles of the optical properties (namely the extinction&#8201;/&#8201;scattering and absorption coefficients; respectively &#963;<sub>ext</sub>&#8201;/&#8201;&#963;<sub>scat</sub>&#8201;/&#8201;&#963;<sub>abs</sub>) of aerosols have been made across the Indo-Gangetic Plain (IGP) using an instrumented aircraft operated from three base stations (Jodhpur (JDR) representing the semiarid western IGP; Varanasi (VNS) the central IGP characterized by significant anthropogenic activities; and the industrialised coastal location in the eastern end of the IGP (Bhubaneswar, BBR)), just prior to the onset of the Indian Summer monsoon. The vertical profiles depicted region-specific absorption characteristics, while the scattering characteristics remained fairly uniform across the region, leading to a west-east gradient in the vertical structure of single scattering albedo (SSA). Integrated from near ground to 3&#8201;km, the highest absorption coefficient and hence the lowest SSA occurred in the central IGP (Varanasi). Size distribution, inferred from the spectral variation of the scattering coefficient, showed a gradual shift from coarse particle dominance in the western IGP to strong accumulation dominance in the eastern coast with the central IGP coming in-between, arising from a change in the aerosol type from predominantly natural (dust and sea-salt) type in the western IGP to highly anthropogenic type (industrial emissions, fossil fuel and biomass combustion) in the eastern IGP; the central IGP exhibiting a mixture of both. Aerosol induced short-wave radiative forcing, estimated using altitude resolved SSA information, revealed significant atmospheric warming in the central IGP while a top-of-atmosphere cooling is seen, in general, in the IGP. Atmospheric heating rate profiles, estimated using altitude resolved SSA and column average SSA, revealed considerable underestimation in the latter case, emphasising the importance and necessity of having altitude resolved SSA information as against a single value for the entire column.</p>
The vertical distribution of aerosol and dust extinction coefficient over the Bay of Bengal is examined using the satellite observations (Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS)) for the period from 2006 to 2017. Distinct seasonal pattern is observed in the vertical structure of both aerosol and dust over the Bay of Bengal with an enhancement of 24% in the aerosol extinction above 1 km from winter (December, January and February) to premonsoon (March, April, and May). Significant contribution of dust is observed over the northern Bay of Bengal during premonsoon season where 22% of the total aerosol extinction is contributed by dust aerosols transported from the nearby continental regions. During winter, dust transport is found to be less significant with fractional contribution of ~10%–13% to the total aerosol optical depth over the Bay of Bengal. MODIS‐derived dust fraction (fine mode based) shows an overestimation up to twofold compared to CALIOP dust fraction (depolarization based), whereas the Goddard Chemistry Aerosol Radiation and Transport‐simulated dust fraction underestimates the satellite‐derived dust fractions over the Bay of Bengal. Though the long‐term variation in dust aerosol showed a decreasing trend over the Bay of Bengal, the confidence level is insufficient in establishing the robustness of the observed trend. However, significant dust‐induced heating is observed above the boundary layer during premonsoon season. This dust‐induced elevated heating can affect the convection over the Bay of Bengal which will have implication on the monsoon dynamics over the Indian region.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.