Rapid Refresh Frequently Asked Questions
Last modified on Friday, 14-Sep-2012 12:29:52 UTC
Q: What different versions of the Rapid Refresh are currently running
as of fall 2012?
A:
- RAP-NCEP - This version is the NCEP operational (implemented 1 May 2012) version
of the RAP. As of that date, the RAP replaced the Rapid Update Cycle as the
NOAA operational hourly updated weather forecast model.
All other versions below run at NOAA/ESRL/Boulder,CO. - RAP-primary - This version is the most "solid" ESRL version of the RAP, and code from the RAP-primary is migrated to the NCEP RAP. Primary differences between RAP-NCEP and RAP-primary-ESRL are listed here . The RAP-primary is used to initialize the 3km HRRR.
- RAP-development - This is a more developmental version of the RAP, and it has been used for variations in data assimilation or model physics. The latest details can be found in the ESRL RAP change log.
- RAP-development-2 - This is another developmental version of the RAP, and has different experiments than the RAP-dev1. Again, the latest details on RAP-dev1 or RAP-dev2 can be found in the ESRL RAP change log.
- RAP - no-cycle (or, RR-cold-start) - This version is initialized from the GFS every 12h. It provides a good comparison with the primary RAP, since it uses the same RR-version of the WRF model. .
A: The RAP grids will be distributed on the grids shown in http://rapidrefresh.noaa.gov/RR-NCEP-grids.txt . Note that the RAP provides look-alike RUC 13km, 20km, and 40km gridded data.
Q: Is the NCEP-provided "RUC40" data going away with the RAP implementation
replacing the RUC?
A: No, since the 40km look-alike grids will still be provided by the RAP
on the same grid points as in the RUC40 (40km-resolution) fields.
Q: What horizontal resolution is the RAP using?
A: 13km, just like the RUC, but, of course,
over a much wider geographic area (all of North America), about 3x larger
than the RUC.
Q: What model does the RAP use?
A:
A RAP-configuration of the WRF model, with
- ARW core (v3.2+ for NCEP-operational version as of April 2012) with
- generally RUC-like physics (Grell-3D convection, Thompson/NCAR microphysics, RRTM longwave radiation, Dudhia shortwave radiation, MYJ turbulent mixing, RUC-Smirnova land-surface model)
- 13-km horizontal resolution, 50 vertical levels, ptop=10hPa, sigma vertical coordinate, 759x568 domain More info here.
- NOTE: ESRL version of RAP uses a more advanced version of the WRF-ARW model, v3.3.1+ as of April 2012.
Q: What is the history of the operational RUC?
- 1994 - RUC starts running at NCEP, first version with 60-km horizontal resolution and 3-h assimilation cycle.
- 1998 - Implementation of 40-km RUC with 1-h assimilation cycle
- 2002 - Implementation of 20-km RUC with 1-h assimilation cycle
- 2005 - Implementation of 13-km RUC with 1-h assimilation cycle
- 2008 - Implementation of major 13km RUC upgrade, including assimilation of radar reflectivity.
- 2012 - Implementation of Rapid Refresh replacing the RUC.