[ncl-talk] problem encountered when converting grib to nc

[HAVENER, KEVIN F GS-12 USAF ACC 14 WS/WXED]

I use ncl_convert2nc all the time in my job.  If ncl_filedump of the grib and resulting nc files give the same information then nothing is wrong with the conversion.  Given the complete "usualness" of NCEP FNL, I suspect a GrADS problem, not an NCL problem.  Can't help you there, not a GrADS user.  

Kevin Havener

-----Original Message-----
From: ncl-talk-bounces at ucar.edu [mailto:ncl-talk-bounces at ucar.edu] On Behalf Of LI Qi
Sent: Wednesday, April 15, 2015 7:45 AM
To: ncl-talk
Subject: [ncl-talk] problem encountered when converting grib to nc

Dear NCL Community,

I use ncl_convert2nc to convert grib formatted NCEP FNL analysis to netcdf file.

Then I open the nc data in GrADS, but its descriptor file is different from the initial grib-formatted one (attached are the two data descriptions). What was wrong?

-------------------------------
description of the grib data
-------------------------------

dset D:\fnl\20110613\fnl_2011%m2%d2_%h2_00_c
index D:\fnl\20110613\fnl_20110613_06_00_c.idx
undef 9.999E+20
title D:\fnl\20110613\fnl_20110613_06_00_c
*  produced by grib2ctl v0.9.12.5p39c
dtype grib 3
options template
options yrev
ydef 181 linear -90.000000 1
xdef 360 linear 0.000000 1.000000
tdef 1 linear 06Z13jun2011 6hr
*  z has 26 levels, for prs
zdef 26 levels
1000 975 950 925 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 70 50 30 20 10 vars 137 no4LFTXsfc  0 132,1,0  ** surface Best (4-layer) lifted index [K] no5WAVA500mb  0 230,100,500 ** 500 mb 5-wave geopot. height anomaly [gpm] no5WAVH500mb  0 222,100,500 ** 500 mb 5-wave geopotential height [gpm] ABSVprs 26 41,100,0 ** (profile) Absolute vorticity [/s] ACPCPsfc  0 63,1,0  ** surface Convective precipitation [kg/m^2] ALBDOsfc  0 84,1,0  ** surface Albedo [%] ...
-------------------------------
description of the converted nc data
-------------------------------
dset D:\fnl\20110613\fnl_20110613_06_00_c.nc
title NCL: convert-GRIB-to-netCDF
undef 1e+20
dtype netcdf
xdef 360 linear 0 1
ydef 181 linear -90 1
zdef 6 levels 100 70 50 30 20 10
tdef 1 linear 00Z01JAN0001 1mn
vars 95
PRES_3_SFC=>pres_3_sfc  0  y,x  Pressure PRES_3_MWSL=>pres_3_mwsl  0  y,x  Pressure PRES_3_TRO=>pres_3_tro  0  y,x  Pressure PRES_3_MSL=>pres_3_msl  0  y,x  Pressure PRES_3_LCBL_ave=>pres_3_lcbl_ave  0  y,x  Pressure PRES_3_LCTL_ave=>pres_3_lctl_ave  0  y,x  Pressure PRES_3_MCBL_ave=>pres_3_mcbl_ave  0  y,x  Pressure PRES_3_MCTL_ave=>pres_3_mctl_ave  0  y,x  Pressure PRES_3_HCBL_ave=>pres_3_hcbl_ave  0  y,x  Pressure PRES_3_HCTL_ave=>pres_3_hctl_ave  0  y,x  Pressure PRMSL_3_MSL=>prmsl_3_msl  0  y,x  Pressure reduced to MSL ...