[Wrf-users] FW: Do these VAR results look normal? -background errorseem increasing.

Kemp, Eric M (IS) ERIC.KEMP at ngc.com
Mon Apr 6 07:15:36 MDT 2009





Abdullah:

What you're seeing is normal.  The Jb term is based on the squared difference between the analysis and the background (A-B)**2.  So as the WRF-Var adjusts the analysis to more closely fit the observations, (A-B)**2 will increase, and so will Jb.  How much weight is given to Jb depends on the background error covariance, along with the observation error covariance used with Jo.

Look at Chapter 9 of the WRF Technical Report for more info on the J equation:

http://www.mmm.ucar.edu/wrf/users/docs/arw_v3.pdf

-Eric

Eric M. Kemp
Meteorologist
Northrop Grumman Information Systems
Advisory Services Division (TASC)
4801 Stonecroft Boulevard
Chantilly, VA 20151
301-286-9768              (NASA Goddard Office)
703-633-8300 x7078 (Chantilly SLEET Lab)
703-633-8300 x8278 (Chantilly Office)
703-449-3400              (Chantilly Fax)



-----Original Message-----
From: wrf-users-bounces at ucar.edu on behalf of Abdullah Kahraman
Sent: Mon 4/6/2009 7:46 AM
To: wrfhelp; wrf-users at ucar.edu
Subject: [Wrf-users] Do these VAR results look normal? -background errorseem increasing.
 
Hello,

After running wrfvar, I have the following cost_fn and grad_fn values.
Background errors seem increasing, isn't this some unexpected thing for an
assimilation?

Regards,
Abdullah KAHRAMAN
Istanbul Technical University
Department of Meteorology




Outer    EPS     Inner      J           Jb       Jo           Jc
Je         Jp
Iter             Iter
   1  0.100E-01     0   1330.654      0.000   1330.654      0.000
0.000      0.000
   1  0.100E-01     1   1192.440      3.507   1188.932      0.000
0.000      0.000
   1  0.100E-01     2   1135.046     10.494   1124.551      0.000
0.000      0.000
   1  0.100E-01     3   1107.064     18.346   1088.717      0.000
0.000      0.000
   1  0.100E-01     4   1097.412     22.466   1074.946      0.000
0.000      0.000
   1  0.100E-01     5   1089.968     26.775   1063.193      0.000
0.000      0.000
   1  0.100E-01     6   1086.380     29.538   1056.842      0.000
0.000      0.000
   1  0.100E-01     7   1083.551     32.328   1051.223      0.000
0.000      0.000
   1  0.100E-01     8   1081.911     34.356   1047.555      0.000
0.000      0.000
   1  0.100E-01     9   1080.408     36.694   1043.714      0.000
0.000      0.000
   1  0.100E-01    10   1079.996     37.447   1042.549      0.000
0.000      0.000
   1  0.100E-01    11   1079.709     38.023   1041.686      0.000
0.000      0.000
   1  0.100E-01    12   1079.522     38.441   1041.080      0.000
0.000      0.000
   1  0.100E-01    13   1079.348     38.885   1040.462      0.000
0.000      0.000
   1  0.100E-01    14   1079.274     39.096   1040.178      0.000
0.000      0.000
   1  0.100E-01    15   1079.217     39.278   1039.939      0.000
0.000      0.000


Outer    EPS     Inner      G           Gb       Go           Ge
Gp
Iter             Iter
   1  0.100E-01     0    104.371      0.000    104.371      0.000      0.000
   1  0.100E-01     1     43.578      2.649     43.658      0.000      0.000
   1  0.100E-01     2     32.406      4.581     32.729      0.000      0.000
   1  0.100E-01     3     26.256      6.057     26.946      0.000      0.000
   1  0.100E-01     4     17.494      6.703     18.734      0.000      0.000
   1  0.100E-01     5     11.674      7.318     13.778      0.000      0.000
   1  0.100E-01     6     11.721      7.686     14.017      0.000      0.000
   1  0.100E-01     7      7.221      8.041     10.808      0.000      0.000
   1  0.100E-01     8      6.672      8.289     10.641      0.000      0.000
   1  0.100E-01     9      4.975      8.567      9.907      0.000      0.000
   1  0.100E-01    10      4.032      8.654      9.547      0.000      0.000
   1  0.100E-01    11      2.293      8.720      9.017      0.000      0.000
   1  0.100E-01    12      2.437      8.768      9.101      0.000      0.000
   1  0.100E-01    13      1.535      8.819      8.951      0.000      0.000
   1  0.100E-01    14      1.586      8.843      8.984      0.000      0.000
   1  0.100E-01    15      1.002      8.863      8.920      0.000      0.000


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/wrf-users/attachments/20090406/14bd8b89/attachment.html 


More information about the Wrf-users mailing list