Evaluation of A Convective Cloud Microphysics Scheme in CAM5 under the CAPT Framework

Abstract:

The goal of this study is to improve the representation of microphysical processes of convection and its interactions with stratiform clouds and aerosols in the GCMs. We use the U.S. DOE Cloud-Associated Parameterizations Testbed (CAPT), which can efficiently run climate models in short-range weather hindcasts, to test the impacts of the convective cloud microphysics scheme on intraseasonal variability (MJO) in the tropics. Two-moment convective cloud microphysics scheme developed by Song and Zhang (2011) and Song et al. (2012) is tested in NSF/DOE CAM5.

Compared to the default model, CAM5 with the convective cloud microphysics scheme produces less precipitation in most tropical oceans but more precipitation over tropical lands. More OLR is seen over the ITCZ regions except over the Maritime Continent (MC). The intraseasonal variability in precipitation is better simulated over the MC (and other continents) in the selected hindcast period (Oct 10-Nov 25, 2009). Stratiform precipitation is enhanced over the MC, consistent with changes in the heating, cloud, and relative humidity profiles. More in-depth analysis is currently being conducted.

(This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.)