Shortwave versus longwave direct radiative forcing by Taklimakan dust aerosols

Abstract

Six Mays from 2001 to 2006 of aerosol optical depth from the Multiangle Imaging SpectroRadiometer and short‐ and longwave flux from the Clouds and Earth's Radiant Energy Budget Scanner are combined to estimate radiative forcing of dust aerosols in the Taklimakan Desert (75°E–95°E, 36°N–42°N, elevation < 1600 m). The cloud‐free dust shortwave versus longwave forcing per aerosol optical depth at about 05:00 UTC are −48.1 and 28.4 W m −2 , respectively. Dust longwave warming offsets 58% of dust shortwave cooling and the overall dust radiative effect is to cool the Earth system. Annual shortwave and longwave forcing efficiencies vary from 26.7 to 63.8 and 18.3 to 39.3 W m −2 , respectively, due to changes in surface properties. Radiative transfer model simulations also suggest Earth's system is cooled in the shortwave but warmed in the longwave by Taklimakan dust aerosols.