[gradsusr] WRF data in grads: Problem with the levels
Masters.Steve
masters.steve at ensco.com
Thu Sep 15 08:58:44 EDT 2011
An alternative to ARWpost that is not talked about much...You can convert WRF data to grib format using the wrfpost program. The wrfpost program interpolates the data to constant pressure surfaces (and other levels as you require) and writes the data in grib. You then use the utilities grib2ctl.pl and gribmap to produce the files needed for grads. Since I'm used to dealing with grib files from NCEP models in grads, I find this approach very workable. You can find the wrfpost program from the WRF-NMM/DTC page at http://www.dtcenter.org/wrf-nmm/users/.
Steve Masters
ENSCO, Inc.
Melbourne, FL
-----Original Message-----
From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Nick Heath
Sent: Thursday, September 15, 2011 8:38 AM
To: GrADS Users Forum
Subject: Re: [gradsusr] WRF data in grads: Problem with the levels
Hey Catherine,
Unfortunately, to extract the height/pressure levels at the model sigma levels, and display WRF data in GrADS, there is an intermediate step. If you go here: http://www.mmm.ucar.edu/wrf/users/ and go to the Download tab, there is a Post-Processing program called ARWPost that converts WRF output into a GrADS friendly binary and even produces the control file for you. As you will see, the control file will look almost identical to the one you created, but will have the extracted pressure/height levels that you specify in the namelist. I have had problems with ARWPost creating really weird output, but I do not think there is any alternative right now if you want to use GrADS.
-Nick
----- Original Message -----
From: Catherine Meissner <catherine at windsim.com>
Date: Thursday, September 15, 2011 8:39 am
Subject: [gradsusr] WRF data in grads: Problem with the levels
To: gradsusr at gradsusr.org
> Hello,
>
>
>
> I am using WRF data files in GrADS version 2.0.a9oga, in windows.
>
> Having been unable to open the WRF files using xdfopen or sdfopen I
> havewritten my own CTL file in order to open the data. Everything
> is working for
> me except that the z levels which the file contains do not seem to
> correspond to the pressure. The nc dump suggests there are 29
> levels (which
> is correct as there were 29 eta levels in the WRF file).
>
> However the range of
>
> these levels is from 2986950,2887400,2787850 ... up to 199550,
> 100000. How
> can these numbers be related to pressure?
>
>
>
> All I need to know is what these Z levels mean and how I can wither
> convertthem to pressure or to height. Thanks for any help offered.
>
>
>
> The Corresponding CTL file is:
>
>
>
> dset ^wrfout_d02_%y4-%m2-%d2_%h2_%n2_00
>
> dtype netcdf
>
> title "Iberdrola data for Jan2008"
>
> undef -1e+30
>
> options template
>
> pdef 140 140 lcc 33.87970 -11.30862777011 1 1 43.427 43.427 -
> 3.839993 10000
> 10000 xdef 140 linear -4.5000000 0.004 ydef 140 linear 41.950000
> 0.0032 zdef
> 30 linear 2986950 2887400,
> 2787850,2688300,2588750,2489200,2389650,2290100,2190550,2091000,1991450,1891
> 800,1792300,1692800,1593250,1493700,1394150,1294600,1195050,1095500,995950,8
> 96400,
>
> 796850,697300,597750,498200,398650,299100,199550,100000
>
> tdef 480 linear 00:00Z01jan2008 1hr
>
>
>
> vars 4
>
> U=>u 29 t,z,y,x westerly wind
>
> V=>v 29 t,z,y,x southerly wind
>
> P=>p 29 t,z,y,x Pressure
>
> T=>t 29 t,z,y,x perturbation potential temperature
> (theta-t0)
>
> Endvars
>
>
>
> the ncdump is:
>
>
>
> netcdf wrfout_d02_2007-12-31_18_00_00 {
>
> dimensions:
>
> Time = UNLIMITED ; // (1 currently)
>
> DateStrLen = 19 ;
>
> west_east = 140 ;
>
> south_north = 140 ;
>
> bottom_top = 29 ;
>
> bottom_top_stag = 30 ;
>
> soil_layers_stag = 4 ;
>
> west_east_stag = 141 ;
>
> force_layers = 8 ;
>
> south_north_stag = 141 ;
>
> variables:
>
> char Times(Time, DateStrLen) ;
>
> float LU_INDEX(Time, south_north, west_east) ;
>
> LU_INDEX:FieldType = 104 ;
>
> LU_INDEX:MemoryOrder = "XY " ;
>
> LU_INDEX:description = "LAND USE CATEGORY" ;
>
> LU_INDEX:units = "" ;
>
> LU_INDEX:stagger = "" ;
>
> LU_INDEX:coordinates = "XLONG XLAT" ;
>
> float ZNU(Time, bottom_top) ;
>
> ZNU:FieldType = 104 ;
>
> ZNU:MemoryOrder = "Z " ;
>
> ZNU:description = "eta values on half (mass)
> levels" ;
>
> ZNU:units = "" ;
>
> ZNU:stagger = "" ;
>
> float ZNW(Time, bottom_top_stag) ;
>
> ZNW:FieldType = 104 ;
>
> ZNW:MemoryOrder = "Z " ;
>
> ZNW:description = "eta values on full (w) levels" ;
>
> ZNW:units = "" ;
>
> ZNW:stagger = "Z" ; (... and many more variables
> listed)
>
> // global attributes:
>
> :TITLE = " OUTPUT FROM WRF V3.1.1 MODEL" ;
>
> :START_DATE = "2007-12-31_18:00:00" ;
>
> :SIMULATION_START_DATE = "2007-12-31_18:00:00" ;
>
> :WEST-EAST_GRID_DIMENSION = 141 ;
>
> :SOUTH-NORTH_GRID_DIMENSION = 141 ;
>
> :BOTTOM-TOP_GRID_DIMENSION = 30 ;
>
> :DX = 10000.f ;
>
> :DY = 10000.f ;
>
> :GRIDTYPE = "C" ;
>
> :DIFF_OPT = 1 ;
>
> :KM_OPT = 4 ;
>
> :DAMP_OPT = 0 ;
>
> :DAMPCOEF = 0.2f ;
>
> :KHDIF = 0.f ;
>
> :KVDIF = 0.f ;
>
> :MP_PHYSICS = 6 ;
>
> :RA_LW_PHYSICS = 1 ;
>
> :RA_SW_PHYSICS = 1 ;
>
> :SF_SFCLAY_PHYSICS = 2 ;
>
> :SF_SURFACE_PHYSICS = 2 ;
>
> :BL_PBL_PHYSICS = 2 ;
>
> :CU_PHYSICS = 0 ;
>
> :SURFACE_INPUT_SOURCE = 1 ;
>
> :SST_UPDATE = 0 ;
>
> :GRID_FDDA = 0 ;
>
> :GFDDA_INTERVAL_M = 0 ;
>
> :GFDDA_END_H = 0 ;
>
> :GRID_SFDDA = 0 ;
>
> :SGFDDA_INTERVAL_M = 0 ;
>
> :SGFDDA_END_H = 0 ;
>
> :SF_URBAN_PHYSICS = 0 ;
>
> :FEEDBACK = 1 ;
>
> :SMOOTH_OPTION = 0 ;
>
> :SWRAD_SCAT = 1.f ;
>
> :W_DAMPING = 0 ;
>
> :MOIST_ADV_OPT = 1 ;
>
> :SCALAR_ADV_OPT = 1 ;
>
> :TKE_ADV_OPT = 1 ;
>
> :DIFF_6TH_OPT = 0 ;
>
> :DIFF_6TH_FACTOR = 0.12f ;
>
> :OBS_NUDGE_OPT = 0 ;
>
> :WEST-EAST_PATCH_START_UNSTAG = 1 ;
>
> :WEST-EAST_PATCH_END_UNSTAG = 140 ;
>
> :WEST-EAST_PATCH_START_STAG = 1 ;
>
> :WEST-EAST_PATCH_END_STAG = 141 ;
>
> :SOUTH-NORTH_PATCH_START_UNSTAG = 1 ;
>
> :SOUTH-NORTH_PATCH_END_UNSTAG = 140 ;
>
> :SOUTH-NORTH_PATCH_START_STAG = 1 ;
>
> :SOUTH-NORTH_PATCH_END_STAG = 141 ;
>
> :BOTTOM-TOP_PATCH_START_UNSTAG = 1 ;
>
> :BOTTOM-TOP_PATCH_END_UNSTAG = 29 ;
>
> :BOTTOM-TOP_PATCH_START_STAG = 1 ;
>
> :BOTTOM-TOP_PATCH_END_STAG = 30 ;
>
> :GRID_ID = 2 ;
>
> :PARENT_ID = 1 ;
>
> :I_PARENT_START = 14 ;
>
> :J_PARENT_START = 10 ;
>
> :PARENT_GRID_RATIO = 5 ;
>
> :DT = 60.f ;
>
> :CEN_LAT = 40.5046f ;
>
> :CEN_LON = -3.839993f ;
>
> :TRUELAT1 = 43.427f ;
>
> :TRUELAT2 = 43.427f ;
>
> :MOAD_CEN_LAT = 43.427f ;
>
> :STAND_LON = -3.84f ;
>
> :POLE_LAT = 90.f ;
>
> :POLE_LON = 0.f ;
>
> :GMT = 18.f ;
>
> :JULYR = 2007 ;
>
> :JULDAY = 365 ;
>
> :MAP_PROJ = 1 ;
>
> :MMINLU = "" ;
>
> :NUM_LAND_CAT = 24 ;
>
> :ISWATER = 16 ;
>
> :ISLAKE = 0 ;
>
> :ISICE = 0 ;
>
> :ISURBAN = 0 ;
>
> :ISOILWATER = 0 ;
>
> }
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Catherine Meissner
> Software Development Manager
>
>
> Fjordgaten 15
> N-3125 Tønsberg, Norway
>
> Switchboard +47 33 38 18 00
>
> <http://www.windsim.com/> www.windsim.com
>
> Email
>
> Direct
>
> Fax
>
>
>
> <mailto:kristine at windsim.com> catherine at windsim.com
>
> +47 33 38 18 06
> +47 33 38 18 08
>
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