NCEP Model Evaluation Subscribers,
The Environmental Modeling Center (EMC) has proposed an upgrade to
the Rapid Update Cycle (RUC).
The changes include:
1. Upgrades to algorithms for RUC analysis
1. Use of mesonet wind data
2. Assimilation of 3-d radar reflectivity
3. Assimilation of TAMDAR aircraft observations including
moisture observations
4. Revision to observation error and background error for
moisture observations
5. Improved QC based on observation-background differences
2. Upgrades to algorithms for RUC model
1. Specification of latent heating from radar reflectivity
during pre-forecast diabatic digital filter initialization
(DFI) already in RUC model
2. Use of RRTM longwave radiation parameterization replacing
current Dudhia longwave radiation, warm bias at surface in
warm season, and decreasing cold bias at night over snow cover
3. Modifications to Grell-Devenyi convective parameterization
to reduce excessive areal coverage for light precipitation
and to introduce non-local subsidence warming
4. Modification to RUC land-surface model for snow density to
prevent excessive surface temperature over fresh snow
3. Upgrade to RUC post-processing code
1. Add 3 reflectivity fields to isobaric (ruc_presm) output
fields for max, 1-km, and 4-km levels, similar to those
products already produced for the NAM
2. Add accumulated total precipitation and snow fields, also
following NAM fields
3. Modify ceiling diagnostic to avoid excessive LIFR (Low
Instrument Flight Rules) conditions. Ed. Pre-processing of
3-d radar reflectivity to ~13km resolution from
higher-resolution tiles **
*N**ear Rea**l-Time Parallel Data*
Beginning Tuesday 16 September 2008, parallel data will be at:
FTP:
ftp://ncep.noaa.gov/pub/data/nccf/com/ruc/test/ruc2a.YYYYMMDD
<http://www.ftp.ncep.noaa.gov/data/nccf/com/ruc/test/ruc2a.YYYYMMDD>
HTTP:
http://www.ftp.ncep.noaa.gov/data/nccf/com/ruc/test/ruc2a.YYYYMMDD
In addition, we are sending GEMPAK data to the WOC at:
FTP:
ftp.ncep.noaa.gov/pub/data/nccf/com/nawips/test/ruc2.YYYYMMDD
<ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nawips/test/ruc2.YYYYMMDD>
HTTP:
http://www.ftp.ncep.noaa.gov/data/nccf/com/nawips/test/ruc2.YYYYMMDD
There are no major scientific changes in this package. We will make the
model output available for 30 days starting Tuesday, 16 September so that
end-users of the RUC data can verify that no unforeseen changes
have been introduced.
Any comments on this proposed change will be appreciated. Any feedback
you wish to provide during the evaluation period should be emailed to
NCEP.List.ModelEvalFeedback@xxxxxxxx
<mailto:NCEP.List.ModelEvalFeedback@xxxxxxxx>, prior to 16 October 2008.
Thanks
Dan Starosta
------------------------------------------------------------------------