[Wrf-users] WPS2.2 / ungrib problem and fix

[Rob Cermak]

Following through the tutorial, I am using a custom grid and NCEP grib2
NAM #242 for testing.  I ran into a slight bug/feature that could trip a
few folks.

During the initial testing, running ungrib.exe did not turn up any useful
data although I was certain it was there and in good order.  Turns out,
the offset used to scan for the 1st grib2 message was too short. 
Increasing the offset from 10 to 100 fixed it.

My offset (lskip) is 33 for this grid.   The symptom before the fix was
ungrib.exe not finding any data.  Raw data from NCEP FTP would probably
have a smaller offset.  We are using data straight from the Unidata/IDD.

2007-02-04 22:25:45.041 --- DEBUG: Reading from gribflnm GRIBFILE.AAA
2007-02-04 22:25:45.041 --- DEBUG: Calling rd_grib2
2007-02-04 22:25:45.041 --- DEBUG: Begin rd_grib2
2007-02-04 22:25:45.041 --- DEBUG: G2 GRIB MESSAGE  1 starts at 33
2007-02-04 22:25:45.074 --- DEBUG: G2 hdate = 2007-02-05_00:00:00
2007-02-04 22:25:45.074 --- DEBUG: G2 hdate (fcst?) = 2007-02-05_00:00:00

--- rd_grib2.F90.orig   2007-02-04 22:22:07.402316000 -0900
+++ rd_grib2.F90        2007-02-04 22:22:59.545794000 -0900
@@ -165,8 +165,9 @@

          ! ----
          ! Once per file fill in date, model and projection values.
+         ! Increase from 10 to 100 for reading grib2 messages from IDD

-         if (lskip.lt.10) then
+         if (lskip.lt.100) then

            ! Build the 19-character date string, based on GRIB2 header date
            ! and time information, including forecast time information:

Have a great week!
Rob
-- 
Alaska Ocean Observing System
Database Manager
907-474-7948 (skype:rob_cermak)