[gradsusr] Different output values from Grads and wgrib2

[Bo Zhang]

Hi great grads users,

I was trying to plot temperature profile with Grads and just found different results from Grads and wgrib2. I am sure that I am reading the same data file. I got the attached profile plot from Grads and the following result from wgrib2 at the same position. One thing should be noticed is that Gtads and wgrib2 number the grid box in different ways. The (0, 0) grid box in Grads (-180:179, -90,90) should be (181,91) in a (0:360, 0,181) system. The bump at 30 mb in the figure exists for any lon-lat position I try, which is wired to me. The other values are also slightly various. 

$ ./wgrib2 ***/Grads/fnl_20100508_06_00 -s -ij 181 91 | grep :TMP
3:120296:d=2010050806:TMP:10 mb:anl::val=240.5
8:393851:d=2010050806:TMP:20 mb:anl::val=220.9
13:666758:d=2010050806:TMP:30 mb:anl::val=215.9
18:961202:d=2010050806:TMP:50 mb:anl::val=204.1
23:1271647:d=2010050806:TMP:70 mb:anl::val=193.5
28:1588656:d=2010050806:TMP:100 mb:anl::val=190.7
36:1997953:d=2010050806:TMP:150 mb:anl::val=207.4
43:2356630:d=2010050806:TMP:200 mb:anl::val=223.1
50:2732191:d=2010050806:TMP:250 mb:anl::val=235.9
57:3106953:d=2010050806:TMP:300 mb:anl::val=244.9
64:3498361:d=2010050806:TMP:350 mb:anl::val=254.5
71:3898258:d=2010050806:TMP:400 mb:anl::val=260.8
78:4302495:d=2010050806:TMP:450 mb:anl::val=266.3
85:4751606:d=2010050806:TMP:500 mb:anl::val=270.9
92:5208947:d=2010050806:TMP:550 mb:anl::val=274.5
99:5689297:d=2010050806:TMP:600 mb:anl::val=277.9
106:6172793:d=2010050806:TMP:650 mb:anl::val=282.1
113:6640256:d=2010050806:TMP:700 mb:anl::val=284.2
120:7112632:d=2010050806:TMP:750 mb:anl::val=286
127:7585314:d=2010050806:TMP:800 mb:anl::val=289.1
134:8055101:d=2010050806:TMP:850 mb:anl::val=291.8
141:8545830:d=2010050806:TMP:900 mb:anl::val=294.6
148:9033256:d=2010050806:TMP:925 mb:anl::val=296.2
155:9515141:d=2010050806:TMP:950 mb:anl::val=297.4
162:9986444:d=2010050806:TMP:975 mb:anl::val=299.5
169:10444342:d=2010050806:TMP:1000 mb:anl::val=301.6


Bo Zhang
Dow 824,Civil and Environmental Engineering
Michigan Tech University
1400 Townsends Drive. 
Houghton, MI, 49931
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