Abstract
Abstract. We describe the development of a non-hydrostatic version of the regional climate model RegCM4, called RegCM4-NH, for use at convection-permitting resolutions. The non-hydrostatic dynamical core of the Mesoscale Model MM5 is introduced in the RegCM4, with some modifications to increase stability and applicability of the model to long-term climate simulations. Newly available explicit microphysics schemes are also described, and three case studies of intense convection events are carried out in order to illustrate the performance of the model. They are all run at a convection-permitting grid spacing of 3 km over domains in northern California, Texas and the Lake Victoria region, without the use of parameterized cumulus convection. A substantial improvement is found in several aspects of the simulations compared to corresponding coarser-resolution (12 km) runs completed with the hydrostatic version of the model employing parameterized convection. RegCM4-NH is currently being used in different projects for regional climate simulations at convection-permitting resolutions and is intended to be a resource for users of the RegCM modeling system.
Highlights
Since the pioneering work of Dickinson et al (1989) and Giorgi and Bates (1989), documenting the first regional climate modeling system (RegCM, version 1) in the literature, the dynamical downscaling technique based on limitedarea regional climate models (RCMs) has been widely used worldwide, and a number of RCM systems have been developed (Giorgi, 2019)
In this paper we have described the development of RegCM4-NH, a non hydrostatic version of the regional model system RegCM4, which was completed in response to the need of moving to simulations at convection-permitting resolutions of a few kilometers
The non-hydrostatic dynamical core of MM5 has been incorporated into the RegCM4 system previously based on the MM5 hydrostatic core
Summary
Since the pioneering work of Dickinson et al (1989) and Giorgi and Bates (1989), documenting the first regional climate modeling system (RegCM, version 1) in the literature, the dynamical downscaling technique based on limitedarea regional climate models (RCMs) has been widely used worldwide, and a number of RCM systems have been developed (Giorgi, 2019). The RCM community is rapidly moving to higher resolutions of a few kilometers, i.e., “convection-permitting” (Prein et al, 2015; Coppola et al, 2020), and the dynamical core of RegCM4 has been upgraded to include a non-hydrostatic dynamics representation usable for very high-resolution applications.
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