Implementation and Evaluation of a Double-Plume Convective Parameterization in NCAR CAM5

Abstract Performance of global climate models (GCMs) is strongly affected by the cumulus parameterization (CP) used. Similar to approach in GFDL AM4, a double-plume CP, which unifies deep and shallow convection one framework, implemented tested NCAR Community Atmospheric Model version 5 (CAM5). Based on University Washington (UW) scheme, an additional plume was added represent convection. The plumes share same cloud model, but use different triggers, fractional mixing rates, closures. scheme single-column, short-term hindcast, AMIP simulations. Compared with default combination Zhang–McFarlane UW CAM5, new tends produce top-heavy mass flux profile during active monsoon period single-column increases intensity tropical precipitation, closer TRMM observations. increased subtropical marine boundary layer clouds high over tropics, both better agreement Sensitivity tests indicate that regime-dependent entrainment rates are desired improve precipitation distribution upper troposphere temperature. This study suggests promising way combine convections unified framework.