Cloud Radiative Forcing in East Asia Simulated from IAP/LASG GCM with a Physics-Based, Two-Moment Statistical-Numerical Cloud Scheme

Abstract:

To improve the treatment of cloud microphysics, a physics-based, two-moment (mass and number) statistical-numerical cloud scheme has been incorporated into IAP/LASG global climate model and simulations conducted to study the model responses. This scheme allows aerosol-cloud interactions through aerosols serving as cloud condensation nuclei. Here we present the results of an analysis of the cloud radiative forcing focusing on East Asia. Compared with the previous treatment of one-moment cloud scheme together with an empirical formula for droplet size, the new scheme simulates larger low cloud cover, liquid water path, and droplet size, which reflect more solar radiation, emit more longwave radiation, thus yield a larger net cloud radiative forcing. We plan to use offline radiation code (RRTMG) to examine the individual effects of cloud cover (low, middle and high) and cloud microphysical properties on the solar and longwave radiation fluxes reaching the surface and their relative roles in affecting the surface temperature. Comparisons with available satellite and ground-based measurements will also be conducted.