Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) Forum
Re: Resolution of RAP data available in archive
Posted By: John Brown In Response To: Resolution of RAP data available in archive (Arthur Pan)
Date: 21-April-21 1822Z
In Response To: Resolution of RAP data available in archive (Arthur Pan)
Thanks for your post. No, you haven’t made a mistake. The old RUC system was indeed run on the 451X337 Lambert-conformal grid (sometimes referred to, in NCEP parlance, as Grid 130) with 50 levels. However, the RAP runs on a much larger domain, covering all of North America, on the 954X835 rotated lat-lon grid you mention, Output from the model forecasts are then interpolated to the smaller 130 grid covering the CONUS and adjacent portions of Canada and Mexico for distribution. Since both the native large grid on which the RAP is actually run, and Grid 130 both use approximately 13km horizontal grid spacing, the interpolation from one to the other does not result in material loss of information.
The 50 layers in the Grid 130 output are the native model layers, so except for vertical velocity, which during the model integration is carried at the 51 layer interfaces, including the bottom and top of the model, there is no vertical interpolation.
Hope this helps!
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