New estimates of aerosol radiative effects over India from surface and satellite observations

Multi year measurements of surface-reaching solar (shortwave) radiation fluxes across a network of aerosol observatories (ARFINET) are combined with concurrent satellite (CERES)-based top of the atmosphere (TOA) fluxes to estimate regional aerosol direct radiative forcing (ARF) over the Indian region. The synergistic approach improves the accuracy of ARF estimates, which otherwise results in an overestimation or underestimation of the atmospheric forcing. During summer, an overestimation of similar to 5 W m(-2) (corresponding heating rate similar to 0.15 K day(-1)) is noticed. The regional average ARF from the synergistic approach reveals the surface forcing reaching -49 W m(-2) over the Indo Gangetic Plains, -45 W m(-2) over northeast India, -34 W m(-2) over the southern Peninsula, and - 16 W m(-2) in the oceanic regions of the Bay of Bengal. The ARF over the northern half of the Indian subcontinent is influenced mainly by anthmpogenic sulfate and carbonaceous aerosols. Dust is dominant in the western region of India during MAM and JJAS. Overall, the clear sky surface reaching solar radiation fluxes is reduced by 3-22% due to the abundance of aerosols in the atmosphere, with the highest reduction over the IGP during autumn and winter.

Automated summary

This study estimates the regional aerosol direct radiative forcing (ARF) in the Indian region using multi-year observations and satellite data. The synergistic approach improves the accuracy of ARF estimates and avoids overestimation or underestimation of atmospheric forcing. The study also reveals that aerosols in the atmosphere reduce the surface solar radiation flux, especially during autumn and winter.