A Refined Understanding of the Ice Cloud Longwave Scattering Effects in Climate Model Academic Article uri icon

abstract

  • AbstractBecause longwave (LW) absorption by greenhouse gases and clouds is more significant than the LW scattering effect by clouds, most climate models neglect cloud LW scattering to save computational costs. Ignoring cloud LW scattering directly overestimates outgoing longwave radiation (OLR). This study included icecloud LW scattering treatment in the Exascale Energy Earth System Model (E3SM) version 2 and ran fullycoupled simulations, prescribed sea surface temperature simulations, and offline radiative transfer calculations to comprehensively assess the impact of icecloud LW scattering on global climate simulation. The instantaneous effect due to icecloud LW scattering reduces the OLR by 1W/m2 on the global average and 2W/m2 on the tropical average. Tropospheric warming and high cloud amount reduction act to partially compensate for such instantaneous OLR reduction caused by the inclusion of LW scattering. When the simulation reaches the equilibrium, the surface warms by 0.66K on average with respect to the simulation without LW scattering, with the Arctic surface temperature differences more than twice as large as that of the global mean. The impact of including LW scattering on the simulated climate change in response to 4CO2 is also assessed. While including the cloud LW scattering does not significantly modify radiative forcing and total radiative feedback under such a scenario, it results in a 10% more positive cloud feedback.

published proceedings

  • JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS

altmetric score

  • 2.25

author list (cited authors)

  • Fan, C., Chen, Y., Chen, X., Lin, W., Yang, P., & Huang, X.

citation count

  • 1

complete list of authors

  • Fan, Chongxing||Chen, Yi-Hsuan||Chen, Xiuhong||Lin, Wuyin||Yang, Ping||Huang, Xianglei

publication date

  • October 2023