Mesoscale Parallel Experiment Change Log

Experiment Name:  North American WRF-NMM with various physics and/or analysis changes

When Who What
2008/11/04/06 Gayno
  • The nam_snow2mdl code, which interpolates the AFWA and NESDIS snow analyses to the NAM native grid, was changed so that it would work using the operational IPOLATES library. Previously, the code would only work with a non-ops version of iplib and thus the code was failing in the NCO parallel NDAS, so snow was continuously cycling on itself. This bug was ONLY in the NDAS parallel run by NCO, not in any EMC NDAS parallels run on dew.
  • 2008/10/28/18 Rogers, Gayno, X. Wang
  • Two changes to the NDAS coldstart script:
    1. The NDAS partial cycling code, replaced in the NDAS by the nam_coldstart code in March 2008, is being reinstated to run after the coldstart code. The nam_coldstart code recomputes the liquid soil moisture in the NDAS history file based on the soil temperature and total soil moisture, using a different formula from that in the NDAS/NAM forecast model. This fix appears to remove 1) a slow drift seen in the bottom layer (100-200 cm) soil temperature, and 2) erratic, unrealistic variability in the NDAS soil moisture. This bug has been in all partial cycling parallels since December 2007.
    2. This script has been modified to bring in the best available NDAS restart file valid at the start time (tm12) of the NDAS, instead of one valid 12-h earlier. This error caused the skin temperature used in the tm12 NDAS analysis first guess to be 12-h out of synch, which will adversely impact assimilation of near-surface satellite radiance channels. This bug was ONLY in the NDAS parallel run by NCO, not in any EMC NDAS parallels run on dew.
  • Cycled NDAS land-states were restarted from the EMC NDAS parallel (which in turn was restarted from ops NDAS land-states at 18z 24 October).
  • 2008/10/20/18 Ferrier, Rogers, X. Wang
  • Fixed a bug in NAM post which excluded the convective precipitation contribution in the computation of simulated radar reflectivity. This was implemented into the operational NAM at 12z 10/28/2008.
  • 2008/10/14/18 Rogers, X. Wang
  • Restarted NDAS cycle (GSI bias correction files, pcpbudget file, and cycled land-states in restart file) from EMC parallel NDAS on dew prior to start of 30-day evaluation period of NAM parallel
  • 2008/10/01/00 Ek, Ferrier, Gayno, Janjic, Pyle, Rogers, Wong, Wu
  • First run of NCO real-time parallel with NAM Fall 2008 Change package, start NDASX with land-states from NDASY parallel
  • The background for the first (tm12) analysis in each NDAS run is now from the GDAS instead of the previous NDAS run (so-called "partial cycling"). Land states are still fully cycled from the previous NDAS run.
  • Changes to WRF-NMM forecast model:
    1. The WRF MYJPBL, PBL driver, and the NMM's TURBL subroutine were modified to mix each hydrometeor species separately in the vertical. The current production code only mixes cloud liquid water.
    2. To apply vertical diffusion for separate water species, the subroutine VDIFH has been changed so that (a) it can handle an arbitrary number of species, (b) the counter gradient option can be applied to some or all of the species if desired, and (c) option to set to zero some or all of the surface fluxes is also made available.
    3. In the radiation parameterization, the absorbtion coefficients for water and ice have been doubled to 1600 and 1000, respectively
    4. Changes to land-sfc physics:
      1. Let ETP (potential evaporation) decrease linearly with Bulk Richardson # under stable condition, and weighted by snow coverage.
      2. Let DQSDT2 (slope of saturated humidity function wrt temperature) decrease linearly with snow coverage.
  • Changes to GSI analysis
    1. Use latest (1Q 2008) version of the GSI analysis code
    2. Assimilate METOP radiance data
    3. Assimilate TAMDAR/AMDAR aircraft data
    4. New verstion of CRTM
  • Use AFWA 1/16 bedient snow depth analysis and a new version of the NAM_SNO2MDL code to process this data.
  • Use WPS (instead of WRF-SI) codes to process GDAS first guess GRIB files into a WRF input file used as a first guess to the first (tm12) GSI analysis in the NDAS