Simulating a Cold-Air Outbreak with SHOC (Simplified Higher-Order Closure)
Authors
Steven K. Krueger — University of Utah
Peter A Bogenschutz — National Center for Atmospheric Research
Category
Shallow-Deep Convective Transition
Description
Cloud water path from a high-resolution, large-eddy simulation of CONSTRAIN case. Domain size is 64 km by 64 km. Such simulations are used as benchmarks for coarse-grid simulations that use SHOC.
The first Grey Zone intercomparison case is based on observations of a cold air outbreak during the CONSTRAIN field campaign. The purpose of this intercomparison is two-fold: Firstly, through systematically varying the horizontal resolution the intercomparison will aim to systematically assess the relative contributions of the resolved and the subgrid-scale (SGS) cloud and convective processes in the Grey Zone for the present CONSTRAIN case. Secondly, the intercomparison is interesting in its own right as it is the first time that we organise a comprehensive mid-latitude cold-air outbreak case. We will use a version of a cloud-resolving model, SAM (System for Atmospheric Modeling), that includes SHOC (Simplified Higher-Order Closure, Bogenschutz and Krueger 2013) which combines several existing components: A prognostic SGS turbulence kinetic energy (TKE) equation, an assumed double-Gaussian PDF following Golaz et al. (2002), the diagnostic second-moment closure of Redelsperger and Sommeria (1986), the diagnostic closure for by Canuto et al. (2001), and a turbulence length scale related to the SGS TKE (Teixeira and Cheinet 2004) and to eddy length scales.
