Mesoscale Parallel Experiment Change Log

Experiment Name:  NAM and DGEX with winter 2005 Eta change package

When Who What
2005/4/30/00 NCO
  • Switched NAM parallel to use parallel T382 GFS for lateral boundary conditions.
  • 2005/4/28/00 NCO
  • Switched DGEX parallel to use parallel T382 GFS for lateral boundary conditions.
  • 2005/3/18/00 Rogers
  • Switched web graphics and real-time verification jobs to use the NCO production parallel NAM and DGEX. A parallel NDAS will still run on blue as a backup to the production parallel NDAS.
  • 2005/3/3/00 Ek, Mitchell
  • Changed value of the leaf-area index from 4.0 to 2.0 in the post-processor so that it is consistent with the value used in the land-surface model. Because of this error the post-processed canopy conductance was twice as large as it should be.
  • 2005/2/10/18 Ek, Mitchell, Rogers
  • Removed this change to subroutine SFCDIF : for the profile functions for the very stable boundary layer (z/L=>1), impose a consistent limit on z0/L. Revert back to ops formulation due to non-meteorological 10-m winds on high mountain peaks.
  • 2005/2/8/18 Rogers
  • Due to system problems causing a break in the full cycle, the NDAS-X cycle was restarted from ops NDAS atmopsheric states and NDAS-X land states.
  • Began use of modified greenness fraction file with corrected values for this parameter north of 58N
  • 2005/1/1/12 Rogers
  • Start of DGEX parallel with winter 2005 change package, consisting of a 00z Alaska DGEX parallel and an 06Z CONUS DGEX parallel.
  • 2004/12/27/12 Bender, Keyser
  • Turned back on use of Level 2.5 NEXRAD data in 3DVAR, only sites with good lat/lon data (about 15-20% of original total) are included in the data dump.
  • 2004/12/10/00 Ferrier
  • Absorption coefficient for ice is made to be the same as in operations.
  • Reset the maximum number concentration of large ice back to 20 per liter as in operations.
  • 2004/12/08/00 Bender, Keyser, Rogers
  • Revert back to ops radial wind data due to 75-85% of the Level 2.5 supob reports in /dcom/us007003/*/b006/xx002 having a missing superob longitude (SUPLON) and a superob latitude (SUPLAT) equal to 65.530 (for every report with a missing SUPLON). It appears that something is corrupt in the incoming Level 2.5 raw files from which SUPLAT and SUPLON are generated.
  • 2004/12/03/12 Ek, Mitchell, Ferrier, Rogers
  • Snow emissivity changes from 0.9 to 0.95
  • 2004/12/03/00 Ek, Mitchell
  • Added the effects of snow emissivity in the calculation of effective snow-ground sfc temperature. This was done by changing the value from 1.0 to 0.9.
  • 2004/12/02/12 Ferrier
  • Changed the standard deviation of RH for grid-scale condensation from 2% to 1%
  • Changed "RHsat=.5*(RHgrd+H1)" to "RHsat=RHgrd", which will have the effect of an earlier onset for partial cloudiness, which will be mitigated by the change in the first bullet.
  • These changes make the cloud cover more "binary"
  • 2004/12/01/00 Ferrier
  • The absorption coefficients for ice are changed back to their earlier values, which are slightly less than what's currently used in the ops Eta.
  • 2004/11/22/12 Ferrier
  • The original exponential factor (0.75) was put back into the relationship used to calculate longwave emissivities from cloud optical depths. This change should have been made along with the other changes on 2004/11/20/12 when reverting back to operational values for cloud calculating cloud optical depths. Prior to this change the solar absorption by clouds was made to be the same as in the EtaZ parallel, but the longwave emissivities were (inadvertently) larger than what's parameterized in operations.
  • 2004/11/20/12 Ferrier
  • Revert back to ops Eta values for the cloud water and cloud ice absorption coefficients
  • Increased the assumed number concentration of cloud droplets from 100 back to 200 /cm**3, which increases the threshold cloud water mixing ratio for autoconversion to rain from 0.419 to 0.838 g/m**3. Also increased the maximum number concentration of precipitation ice particles from 10 back to 20 per liter.
  • 2004/11/16/12 Ferrier, Manikin
  • Added changes to forecast model and pre-processing to output convective rain rate, to use convective rain rate in the visibility algorthim, and to output instantaneous TOA outgoing long-wave radiation.
  • 2004/11/05/12 Ferrier
  • Decreased the assumed number concentration of cloud droplets from 200 to 100 /cm**3, which reduces the threshold cloud water mixing ratio for autoconversion to rain from 0.838 to 0.419 g/m**3. Also decreased the maximum number concentration of precipitation ice particles from 20 to 10 per liter. Both changes are intended to lower the amount of suspended condensate in the atmosphere, which should help reduce the cool bias that has developed below clouds in the parallel.
  • Fixed a minor bug in ADJPPT1 that limits the amount of cloud water from exceeding the autoconversion threshold
  • A new cloud cover scheme is introduced in order to increase the presence of forecast partial cloudiness. Two adjustable parameters in the scheme have been tuned to match the AFWA total cloud cover product. The first parameter (STSDM) is the assumed standard deviation of total grid-scale relative humidity in the grid box, and it is set to 2%. The second parameter (RHsat) is the total relative humidity associated with an assumed cloud fraction of 50%, and it is set to the average of the threshold relative humidity for the onset of grid-scale condensation (RHgrd) and a value of 100% (i.e., 98.3% for the 32-km runs).
  • In calculating longwave emissivities in cloudy layers, the optical depths for cloud water are obtained using the downwelling longwave (LW) relationships of Smith and Shi (1992). This change has resulted in nearly a factor of two increase in the LW absorption coefficient for cloud water. The LW absorption coefficient for ice remains the same as what's currently running in the operational Eta
  • In calculating solar absorption, the optical depths for cloud water and for ice (cloud ice and snow) are obtained using the relationships described by eqs. (5.2), (5.3), and Table 9 from Hou et al. (2002), assuming a constant effective radius of 10 microns for cloud water and 75 microns for ice. For cloud water optical depths, equal weighting is assumed for absorption of UV-VIS and near IR radiation. The net effect of this change is to double the solar absorption from liquid water clouds and halve the absorption from ice clouds.
  • In the operational radiation, a minimum optical depth is assumed for grid-scale liquid water clouds consistent with a minimum mixing ratio of 0.1 g/kg. This lower limit has been removed.
  • Page Last Modified: November 11, 2005