Recent trend in the global distribution of aerosol direct radiative forcing from satellite measurements

Abstract

Global distribution of aerosol direct radiative forcing (DRF) is estimated using Clouds and Earth's Radiant Energy System (CERES) synoptic (SYN) 1° datasets. During 2001–2017, a statistically significant change of global DRFs is revealed with a general decreasing trend (i.e., a reduced cooling effect) at the top of the atmosphere (DRFTOA ~ 0.017 W⋅m−2⋅year−1) and at the surface (DRFSFC ~ 0.033 W⋅m−2⋅year−1) with rapid change over the land compared to the global ocean. South Asia and Africa/Middle East regions depict significant increasing trend of atmospheric warming by 0.025 and 0.002 W·m−2⋅year−1 whereas, the rest of the regions show a decline. These regional variations significantly modulate the global mean DRF (−5.36 ± 0.04 W·m−2 at the TOA and − 9.64 ± 0.07 W·m−2 at the surface during the study period). The observed DRF trends are coincident with the change in the underlying aerosol properties, for example, aerosol optical depth, Ångström exponent and partly due to the increasing columnar burden of SO2 over some of the regions. This indicates that increasing industrialization and urbanization have caused prominent change in the DRF during recent decades. Change in the underlying aerosol properties are synchronous with the change in the forcing.