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RegCM3 is a 3-dimensional, sigma-coordinate, primitive equation regional climate model. It is developed and supported by scientists inside and outside of PWC/ICTP.

1993 flood
Observed and RegCM3-Simulated Precipitation, Flood of 1993.
(Click on image to view larger size version.)
Download Latest Version: regcm.tar.gz (updated 16 June 2006)
Model Data

RegCM3 Tutorial: Detailed example of how to run RegCM3

Model Documentation

RegCM3: Description

For a full description, please see the model documentation (pdf/ps).

RegCM3 History

The first version of the RegCM series was completed by Dickinson et al. (1989), Giorgi and Bates (1989), and Giorgi (1990) at the National Center for Atmospheric Research (NCAR). It was built upon the NCAR-Pennsylvania State University (PSU) Mesoscale Model version 4 (MM4) (Anthes et al. 1987). However, to adapt the MM4 to long-term climate simulations, the radiative transfer package of Kiehl et al. (1987) was added along with Biosphere-Atmosphere Transfer Scheme (BATS) version 1a (Dickinson et al. 1986). In addition, the existing convective precipitation (Anthes 1977) and planetary boundary layer (PBL) (Deardorff 1972) parameterizations were improved upon. The second version of the RegCM series was developed by Giorgi et al. (1993a,b). The dynamical core was upgraded to the hydrostatic version of the NCAR-PSU Mesoscale Model version 5 (MM5) (Grell et al. 1994). The radiative transfer package was also upgraded according to that of Community Climate Model version 2 (CCM2) (described by Briegleb (1992)). The Grell (1993) convective parameterization was included as an option, and the explicit cloud and precipitation scheme of Hsie et al. (1984) was used. BATS was updated from version 1a to 1e (Dickinson et al. 1993) and the non-local PBL parameterization of Holtslag et al. (1990) was implemented. An intermediate version, REGional Climate Model version 2.5 (RegCM2.5), was developed as described in Giorgi and Mearns (1999). It included an option for the Zhang and McFarlane (1995) convection scheme, the Community Climate Model version 3 (CCM3) radiative transfer package (Kiehl et al. 1996), a simplified version of the Hsie et al. (1984) explicit cloud and precipitation scheme (SIMEX) (Giorgi and Shields 1999), and a simple interactive aerosol model (Qian and Giorgi 1999).

RegCM3 is an integration of the main improvements that have been made to RegCM2.5 since the description in Giorgi and Mearns (1999). These improvements are in the representation of precipitation physics, surface physics, atmospheric chemistry and aerosols, model input fields, and the user interface. In addition, the dynamical code has been modified for parallel computing. An important aspect of the RegCM3 is that it is user-friendly and operates on a variety of computer platforms. To that end, substantial changes have been made to the pre-processing, running, and post- processing of the model. Furthermore, the RegCM3 has options to interface with a variety of reanalysis and General Circulation Model (GCM) boundary conditions.