Construction of a Single-Column Model in RegCM4 and its Preliminary Application for Evaluating PBL Schemes in Simulating the Dry Convection Boundary Layer

TL;DR

This paper develops a single-column model in RegCM4 to evaluate different planetary boundary layer schemes by comparing their simulation of dry convection boundary layers against high-resolution LES benchmarks.

Contribution

The study constructs and validates a single-column model in RegCM4 for evaluating PBL schemes using LES benchmarks, providing a new tool for boundary layer process analysis.

Findings

YSU scheme best reproduces LES results

UW09 performs second best

SCM framework shows promising validation results

Abstract

A single-column model (SCM) is constructed in the regional climate model RegCM4. The evolution of a dry convection boundary layer (DCBL) is used to evaluate this SCM and compare four planetary boundary layer (PBL) schemes, the Holtslag-Boville scheme (HB), Yonsei University scheme (YSU), and two University of Washington schemes (UW01, Grenier-Bretherton-McCaa scheme and UW09, Bretherton-Park scheme), using the SCM approach. A large-eddy simulation (LES) of the DCBL is performed as a benchmark to examine how well a PBL parameterization scheme reproduces the LES results, and several diagnostic outputs are compared to evaluate the schemes. In general, with the DCBL case, the YSU scheme performs best for reproducing the LES results, which include well-mixed features and vertical sensible heat fluxes; UW09 has the second best performance, UW01 has the third best performance, and the HB scheme has the worst performance. The results show that the SCM is proper constructed. Although more cases and further testing are required, these simulations show encouraging results towards the use of this SCM framework for studying the physical processes in RegCM4.