North American Regional Climate Change Assessment Program
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Model Changes
 

Two of the regional climate models used in NARCCAP have had changes made to their configurations since the beginning of the program. In both cases, the changes were made after an initial run using NCEP boundary conditions was completed and data from that run published.

Rather than rescinding the data from the original model runs and replacing it, the updated models used to complete the NARCCAP suite of simulations have been given a new 4-letter designation to distinguish them from the original model. Data from the original NCEP-driven runs will remain available.

WRFP has been superseded by WRFG.
ECPC has been superseded by ECP2.

Note that updates to the NARCCAP website to reflect this change are not yet complete.

ECPC vs ECP2

Data from the Regional Spectral Model was originally designated ECPC, for the Experimental Climate Prediction Center at Scripps Institute of Oceanography, where this model was run. Data from the updated model has been designated ECP2.

The main difference between ECPC and ECP2 concerns how spectral nudging was employed. Spectral nudging forces the regional model solution to follow closely its driven global model for scales usually close to and above the synoptic scale. The ECPC-RSM's standard version of spectral nudging combines a spectral damping of horizontal wind tendency and areal average correction of temperature, moisture, and surface pressure. In ECP2, the moisture correction component of the spectral nudging was not used, resulting in better simulation of precipitation. ECP2 also has a larger domain than ECPC, more closely matching the region modeled by the other RCMs.

WRFP vs WRFG

Data from the Weather Research & Forecasting model was originally designated WRFP, the P standing for PNNL (Pacific Northwest National Lab), the home of the modeling group running this model. Data from the updated model has been designated WRFG.

In the WRFP run, the model used the Kain-Fritsch convective parameterization scheme. The updated model uses the Grell scheme instead, which improves the reproduction of temperature and precipitation. The G in WRFG stands for Grell.

References:

Kain, J. S., 2004: "The Kain-Fritsch convective parameterization: An update." J. Appl. Meteor., 43, 170-181.

Grell, G.A. and D. Devenyi, 2002: "A generalized approach to parameterizing convection combining ensemble and data assimilation techniques." Geophys. Res. Lett., 29, 1693-1697.

 
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