Land Cover Regulates the Spatial Variability of Temperature Response to the Direct Radiative Effect of Aerosols

Abstract

Abstract Aerosol impact on the surface temperature varies between the shortwave and the longwave components of radiation, depends on the time of the day, and is modulated by underlying biophysical processes. We disentangle these complexities by isolating the direct surface shortwave and longwave radiative effects from a global reanalysis data product and calculating their spatially explicit climate sensitivities. Higher sensitivity is found for the longwave component and is driven by a combination of spatial variability of aerosol species and biophysical control of the underlying surface. The opposing shortwave and longwave effects reduce the global terrestrial mean diurnal temperature range by 0.47 K, with almost half the contribution in the regions of interest considered coming from aerosols of anthropogenic origin. We also find evidence of an increasing trend in the local climate sensitivity in the equatorial zone, possibly caused by deforestation. These surface processes can partially explain why the climate forcing efficacy of aerosols exceeds unity.

Keywords

• Aerosols
• Biophysical control
• Radiative forcing
• Climate sensitivity
• Surface temperature