Spatial Resolution Dependence of Convective Organization Parameterization in CAM5

Abstract:

This study investigates the role of convective organization at various spatial resolutions, using a unique parameterization of convective organization Ω as a prognostic variable in the Community Atmosphere Model. A unified shallow+deep convection scheme (a N-plume version of the University of Washington shallow convection scheme, currently with N=2) has Ω governing the properties and relative contributions of the plumes. Rain evaporation is the main source of convective organization, and the functions of organization within a plume ensemble include 1) plume radius enhancement (entrainment rate reduction) 2) the plume coverage (area or mass) that reaches the Level of Free Convection, and 3) the probabilities of overlap, and thus interactions, between plume ensemble members. Following from previous works (Mapes and Neale 2011, Chen and Mapes 2014), which used constant, linear coefficients to link Ω to the aforementioned functions, we test resolution-dependent and spatially-dependent coefficients for these functions to probe, and try to improve, simulations of regional climate systems such as South Asian Summer Monsoon.