Mesoscale Parallel Experiment Change Log

Experiment Name:  Eta-32 with assimilation of NEXRAD radial winds

When Who What
2002/02/26/00 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.
  • Cycled EDAS restarted from ETAV control.
  • 2002/03/11/12 Parrish
  • Fixed 3dvar code errors so that the new radiance channels would be correctly processed. Bias corrections were spun up from zero and the Cycled EDAS restarted from ETAV control run.
  • 2002/03/15/12 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.
  • 2002/03/16/00 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.
  • 2002/04/12/00 Parrish, Rogers
  • Turned on use overland GOES precipitable water retrieval data in the eta 3DVAR analysis.
  • 2002/04/15/12 Parrish
  • Turned off use of GOES/TOVS radiances over land
  • 2002/04/16/12 Parrish, Rogers
  • Since the parallel is no longer using overland GOES radiances, job reverts to using the production EDAS/Eta prepbufr files.
  • 2002/04/18/12 Parrish
  • In order to successfully process radiance data for the regional reanalysis, it was necessary to be more aggressive with the evolution of the bias correction. The changes to the radiance processing make the 3dvar more robust, especially when starting a new experiment, when the bias correction is unknown, and some spinup was required. The new version does a spinup automatically every analysis, even though this is redundant most of the time.

    The principle change is as follows: the radiance processing subroutine is iterated 5 times, with observation error and QC limits mutiplied by factors of 5,4,3,2,1 for each iteration. The bias correction is estimated after each pass without going through the entire analysis. This correction is blended with a running average of the input bias correction, with a 1/e time of 15 days. This becomes the new guess bias correction. The analysis bias correction is then generated the same as before. There is also a fixed bias file, which used to be the file eta_satangbias_16_new.txt. This file is no longer used. The fixed bias numbers are now allowed to evolve with a 1/e time of 30 days. They are running means of a mean lapse rate of the background for each channel, and mean difference of obs - guess brightness temperature for each scan angle of each channel.

    The format of the files "satbias_in" and "satbias_out" has been changed to contain all the information necessary for doing running means of the bias coefficients and the angle dependent biases. Each channel is processed independently, and there is a "model id" which is a unique number generated from resolution and position parameters, so that if the model is changed, the file will be reset to zero automatically by the analysis.

    The cycled EDAS was restarted from the 32-km control run (ETAV)

  • Page Last Modified: April 19, 2002