Nonlinear hydrostatic conditional symmetric instability: implications for numerical weather prediction

Abstract

A simplified two-dimensional version of the Pennsylvania State University-NCAR Mesoscale Model was used to investigate the nonlinear evolution of unforced conditional symmetric instability (CSI). Sensitivity tests examines the effects of the model resolution, the magnitudes and formulation of the vertical and horizontal diffusion, and the Prandtl number on various aspects of the CSI circulations. Aspects of the circulations that are considered include the transverse velocity, the growth rate, and the updraft slope, as well as the existence of a CSI circulation. -from Authors