Mesoscale Parallel Experiment Change Log

Experiment Name:  Eta-10 Central nest with NEXRAD Winds

When Who What
2002/02/01/12 Facey Corrected an error in the radial wind BUFR processing which produced an erroneous value for the azimuth angle.
2002/02/06/12 Parrish Corrected an error in the 3dvar code, in which the code was assuming the azimuth angle was defined as positive counterclockwise from the east, when in reality it has the same definition as the actual radar data (positive clockwise from the north).
2002/02/20/12 Parrish
  • Define radar beam vertical extent to increase at the rate of 20m/km. This is about 20% larger than the actual beam size, to allow for beam propagation uncertainty.
  • Winds at all eta levels covered by the radar beam are adjusted so that the observation is as close as possible to the interval between the minimum and maximum wind at the selected levels. (The min and max are not the actual min and max but those derived from a straight line fit to the winds. This is done to simplify the computation of the gradient of the forward model implied by this process).
  • All winds, out to the maximum range of the radar can be used with the above defined forward model. Bill Facey increased the distance parameter in the superob code so that superobs are formed out to the maximum radar range (250km).
  • All VAD wind observation quality marks are collocated in the vertical in 500m bins with the corresponding radar winds. If there is no VAD observation, or if the quality mark is larger than 3, then the corresponding radar winds are not used. This combines the bird algorithm and other checks used on the VAD winds.
  • If the beam envelope extends below the eta model terrain height, the corresponding radar wind is not used.
  • If the superob error is larger than 6m/sec, the radar wind is not used.
  • Gross checks are the same as for conventional winds (residual < 35m/sec)
  • 2002/02/21/12 Rogers Switch from using 00-h Eta-12 initial conditions to 12 km EDAS first guess for background to 10 km analysis.
    2002/02/25/12 Parrish, Pondeca
  • The radar wind 3dvar has been changed to simplify and improve the analysis of the radar data.
  • The earlier version used a linear fit of the model wind profile in determining an estimate of the maximum and minimum wind in the profile. This was done to simplify the gradient computation of the forward model, but has the disadvantage that for deep layers (broad radar beam far from the radar), internal maxima will be missed by the linear fit. The new version eliminates fitting of the profile and just obtains the actual maximum and minimum profile values and the corresponding eta level index of maximum/minimum. This actually leads to a much simpler gradient for the forward model and significantly improved fits of both guess and analysis to the observations.
  • Two code changes have been incorporated related to bugs found in anisotropic testing by Manuel Pondeca. These bugs don't influence the current isotropic mode, but it was important to fix them anyway so they don't creep back in later.
  • 2002/03/06/12 Parrish
  • A diagnostic output file has been added to the radar wind 3dvar for use by Ying Lin to make various graphic displays of the radar data.
  • The radiance processing code has been upgraded to the final global analysis version which is about to be implemented in operations. Key additions include a new land surface emissivity calculation, which allows for use of more observations over land, and the turning on of NOAA 16 HIRS data.
  • Since the new radiance processing has the new land surface emissivity calculation, GOES moisture channels over land are usable. Therefore, assimilation of GOES precipititble water data over land has been turned off.
  • 2002/03/11/12 Parrish
  • Fixed 3dvar code errors so that the new radiance channels would be correctly processed.
  • 2002/03/16/12 Keyser, Parrish, Rogers
  • Modified 3dvar code so that it would use GOES radiances over land. Added prepbufr generation job to the parallel with modified parameter cards so that over-land GOES radiances would be turned on in the prepbifr file.
  • 2002/03/17/12 Parrish
  • A small bug was uncovered in the test 3dvar with new radiance processing. An index was off by one, having a small impact on two of the scan-angle dependent radiance bias correctors. It has been corrected in all parallels currently testing the new 3dvar. This problem is not present in the operational code.
  • 2002/04/12/12 Parrish, Rogers
  • Turned on use overland GOES precipitable water retrieval data in the eta 3DVAR analysis.
  • Page Last Modified: March 6, 2002