Estimates of direct radiative forcing due to aerosols from the MERRA-2 reanalysis over the Amazon region

Abstract. Sixteen years of analysis of clear-sky direct aerosol radiative forcing is presented for the Amazon region, with calculations of AERONET network, MODIS sensor and MERRA-2 reanalysis data. The results showed that MERRA-2 reanalysis is an excellent tool for calculating and providing the spatial distribution of aerosol direct radiative forcing. In addition, the difference between considering the reference state of the atmosphere without aerosol loading and with natural aerosol to obtain the aerosol direct radiative forcing is discussed. During the dry season, the monthly average direct forcing at the top of atmosphere varied from −9.60 to −4.20 Wm⁻², and at the surface, it varied from −29.81 to −9.24 Wm⁻², according to MERRA-2 reanalysis data and the reference state of atmosphere without aerosol loading. Already with the state of reference being the natural aerosols, the average direct forcing at the top of atmosphere varied from −5.15 to −1.18 Wm⁻², and at the surface, it varied from −21.28 to −5.25 Wm⁻²; this difference was associated with the absorption of aerosols.