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[IDV #XBG-435230]: Need help viewing data values



Hi Julie-

Thanks for the sample file.

> Hi.  I am a new IDV user.  I have been checking the mailing list for the
> IDV, but haven't found a solution to my problem (unable to view values
> of data).  I have a netcdf file that I am working on making CF compliant
> and is derived from WRF-RR native grid grb2 files.  I have attached the
> header information.
> 
> I can view 3D and 2D fields under the "Field Selector", however, when I
> select a 3D field to view and double click on "Data Probe/Time Series" I
> receive the message "Unknown vertical coordinate with Unit, using linear
> scale to Altitude".  In the probe window, under "Value", I always see
> "missing".

The problem is that we don't handle non-pressure or altitude levels very well.  
What happens is that the unknown vertical coordinate gets linearly scaled to 
the vertical axis as altitude in meters.  So, in your case, you have sigma 
levels from 1E-4 to 5E-3.  However, the IDV display doesn't autoscale and the 
default is 0-16000 m.

When you create the probe, you'll see that the default level is the probe 
position in the box.  By default, it's halfway up the box which is 8000 meters. 
 That's outside the range of your scaled data.  You can do the following:

- select a particular sigma level in the probe that you want to probe on
- change the vertical scale in the view window (View->Viewpoint->Vertical 
Scale) to be from 1E-4 to 5E-3 and then use the Probe's level as you drag the 
probe around in the box.  A problem with this option is that the formatting of 
the probe level in the table is not sufficient to show the actual level.  For 
this data, it will always show
0.0.

> Based on the error, I believe there is a problem with the lv_SIGL0 and
> lv_SIGL3 units.  The documentation at
> http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#coards-relationship
> says that units attribute is allowed to be "sigma_level" to be backwards
> compatible (although it is not recommended), so I tried changing
> lv_SIGL0:units = "" ; and lv_SIGL3:units = "" ;  to
> lv_SIGL0:units = "sigma_level" ; and lv_SIGL3:units = "sigma_level" ;
> respectively, however this did not solve the problem.
> 
> I also added the attributes lv_SIGL0:formula_terms = "sigma: lv_SIGL0" ;
> and lv_SIGL3:formula_terms = "sigma: lv_SIGL3" ; however this did not
> solve my problem either.

I don't see enough information in the file to convert sigma level to pressure 
or altitude.  The formula usually specifies the top (PTOP) and surface (PS) 
pressure:

 lev:formula_terms = "sigma: lv_SIGL0 ps: PS ptop: PTOP" ;

so the actual pressure can be calculated from that.

> Any feedback you could provide would be greatly appreciated.

Don Murray

> --
> Julie Prestopnik                                      ph  303 497 8399
> Software Engineer
> Research Applications Laboratory
> National Center for Atmospheric Research
> 3450 Mitchell Lane
> Boulder, CO 80301
> 
> netcdf \20100115_i15_f000_WRF-RR.cnv {
> dimensions:
> y = 337 ;
> x = 451 ;
> lv_SIGL0 = 50 ;
> lv_SPDL1 = 3 ;
> lv_HTGL2 = 2 ;
> lv_SIGL3 = 49 ;
> lv_DBLL4 = 5 ;
> variables:
> float La1 ;
> La1:long_name = "latitude of first grid point" ;
> La1:units = "degrees_north" ;
> float Lo1 ;
> Lo1:long_name = "longitude of first grid point" ;
> Lo1:units = "degrees_east" ;
> float Lov ;
> Lov:long_name = "longitude of central meridian" ;
> Lov:units = "degrees_east" ;
> float Dx ;
> Dx:long_name = "x-direction grid length" ;
> Dx:units = "m" ;
> float Dy ;
> Dy:long_name = "y-direction grid length" ;
> Dy:units = "m" ;
> float Latin1 ;
> Latin1:long_name = "first intersecting latitude" ;
> Latin1:units = "degrees_north" ;
> float Latin2 ;
> Latin2:long_name = "second intersecting latitude" ;
> Latin2:units = "degrees_north" ;
> float lv_SIGL0(lv_SIGL0) ;
> lv_SIGL0:units = "" ;
> lv_SIGL0:long_name = "Sigma level (sigma value)" ;
> lv_SIGL0:positive = "up" ;
> lv_SIGL0:standard_name = "atmosphere_sigma_coordinate" ;
> lv_SIGL0:formula_terms = "sigma: lv_SIGL0" ;
> float lv_SPDL1_l0(lv_SPDL1) ;
> lv_SPDL1_l0:units = "Pa" ;
> lv_SPDL1_l0:long_name = "Level at specified pressure difference from ground 
> to level" ;
> float lv_SPDL1_l1(lv_SPDL1) ;
> lv_SPDL1_l1:units = "Pa" ;
> lv_SPDL1_l1:long_name = "Level at specified pressure difference from ground 
> to level" ;
> float lv_HTGL2_l0(lv_HTGL2) ;
> lv_HTGL2_l0:units = "m" ;
> lv_HTGL2_l0:long_name = "Specified height level above ground" ;
> float lv_HTGL2_l1(lv_HTGL2) ;
> lv_HTGL2_l1:units = "m" ;
> lv_HTGL2_l1:long_name = "Specified height level above ground" ;
> float lv_SIGL3(lv_SIGL3) ;
> lv_SIGL3:units = "" ;
> lv_SIGL3:long_name = "Sigma level (sigma value)" ;
> lv_SIGL3:positive = "up" ;
> lv_SIGL3:standard_name = "atmosphere_sigma_coordinate" ;
> lv_SIGL3:formula_terms = "sigma: lv_SIGL3" ;
> float lv_DBLL4(lv_DBLL4) ;
> lv_DBLL4:units = "m" ;
> lv_DBLL4:long_name = "Depth below land surface" ;
> double reference_time ;
> reference_time:long_name = "reference time" ;
> reference_time:units = "hours since 1970-01-01T00:00:00Z" ;
> double forecast_time ;
> forecast_time:long_name = "forecast time" ;
> forecast_time:units = "hours since 1970-01-01T00:00:00Z" ;
> double lat(y, x) ;
> lat:units = "degrees_north" ;
> lat:long_name = "latitude coordinate" ;
> lat:standard_name = "latitude" ;
> double lon(y, x) ;
> lon:units = "degrees_east" ;
> lon:long_name = "longitude coordinate" ;
> lon:standard_name = "longitude" ;
> int Lambert_Conformal ;
> Lambert_Conformal:grid_mapping_name = "lambert_conformal_conic" ;
> Lambert_Conformal:standard_parallel = 25. ;
> Lambert_Conformal:longitude_of_central_meridian = 265. ;
> Lambert_Conformal:latitude_of_projection_origin = 25. ;
> Lambert_Conformal:GRIB_earth_shape = "spherical" ;
> Lambert_Conformal:GRIB_earth_shape_code = 0 ;
> float HGT_P0_L104_GLC0(lv_SIGL0, y, x) ;
> HGT_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> HGT_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 3, 5 ;
> HGT_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Mass" ;
> HGT_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> HGT_P0_L104_GLC0:coordinates = "lat lon" ;
> HGT_P0_L104_GLC0:_FillValue = 1.e+20f ;
> HGT_P0_L104_GLC0:units = "gpm" ;
> HGT_P0_L104_GLC0:long_name = "Geopotential height" ;
> HGT_P0_L104_GLC0:production_status = "Operational products" ;
> HGT_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float PRES_P0_L104_GLC0(lv_SIGL0, y, x) ;
> PRES_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> PRES_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 3, 0 ;
> PRES_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Mass" ;
> PRES_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> PRES_P0_L104_GLC0:coordinates = "lat lon" ;
> PRES_P0_L104_GLC0:_FillValue = 1.e+20f ;
> PRES_P0_L104_GLC0:units = "Pa" ;
> PRES_P0_L104_GLC0:long_name = "Pressure" ;
> PRES_P0_L104_GLC0:production_status = "Operational products" ;
> PRES_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float TMP_P0_L104_GLC0(lv_SIGL0, y, x) ;
> TMP_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> TMP_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 0, 0 ;
> TMP_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Temperature" ;
> TMP_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> TMP_P0_L104_GLC0:coordinates = "lat lon" ;
> TMP_P0_L104_GLC0:_FillValue = 1.e+20f ;
> TMP_P0_L104_GLC0:units = "K" ;
> TMP_P0_L104_GLC0:long_name = "Temperature" ;
> TMP_P0_L104_GLC0:production_status = "Operational products" ;
> TMP_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float SPFH_P0_L104_GLC0(lv_SIGL0, y, x) ;
> SPFH_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> SPFH_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 1, 0 ;
> SPFH_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Moisture" ;
> SPFH_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> SPFH_P0_L104_GLC0:coordinates = "lat lon" ;
> SPFH_P0_L104_GLC0:_FillValue = 1.e+20f ;
> SPFH_P0_L104_GLC0:units = "kg kg-1" ;
> SPFH_P0_L104_GLC0:long_name = "Specific humidity" ;
> SPFH_P0_L104_GLC0:production_status = "Operational products" ;
> SPFH_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float UGRD_P0_L104_GLC0(lv_SIGL0, y, x) ;
> UGRD_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> UGRD_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 2, 2 ;
> UGRD_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Momentum" ;
> UGRD_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> UGRD_P0_L104_GLC0:coordinates = "lat lon" ;
> UGRD_P0_L104_GLC0:_FillValue = 1.e+20f ;
> UGRD_P0_L104_GLC0:units = "m s-1" ;
> UGRD_P0_L104_GLC0:long_name = "u-component of wind" ;
> UGRD_P0_L104_GLC0:production_status = "Operational products" ;
> UGRD_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float VGRD_P0_L104_GLC0(lv_SIGL0, y, x) ;
> VGRD_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> VGRD_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 2, 3 ;
> VGRD_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Momentum" ;
> VGRD_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> VGRD_P0_L104_GLC0:coordinates = "lat lon" ;
> VGRD_P0_L104_GLC0:_FillValue = 1.e+20f ;
> VGRD_P0_L104_GLC0:units = "m s-1" ;
> VGRD_P0_L104_GLC0:long_name = "v-component of wind" ;
> VGRD_P0_L104_GLC0:production_status = "Operational products" ;
> VGRD_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float VVEL_P0_L104_GLC0(lv_SIGL0, y, x) ;
> VVEL_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> VVEL_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 2, 8 ;
> VVEL_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Momentum" ;
> VVEL_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> VVEL_P0_L104_GLC0:coordinates = "lat lon" ;
> VVEL_P0_L104_GLC0:_FillValue = 1.e+20f ;
> VVEL_P0_L104_GLC0:units = "Pa s-1" ;
> VVEL_P0_L104_GLC0:long_name = "Vertical velocity pressure" ;
> VVEL_P0_L104_GLC0:production_status = "Operational products" ;
> VVEL_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float CLMXR_P0_L104_GLC0(lv_SIGL0, y, x) ;
> CLMXR_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> CLMXR_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 1, 
> 22 ;
> CLMXR_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Moisture" ;
> CLMXR_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> CLMXR_P0_L104_GLC0:coordinates = "lat lon" ;
> CLMXR_P0_L104_GLC0:_FillValue = 1.e+20f ;
> CLMXR_P0_L104_GLC0:units = "kg kg-1" ;
> CLMXR_P0_L104_GLC0:long_name = "Cloud mixing ratio" ;
> CLMXR_P0_L104_GLC0:production_status = "Operational products" ;
> CLMXR_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float TKE_P0_L104_GLC0(lv_SIGL3, y, x) ;
> TKE_P0_L104_GLC0:level_type = "Sigma level (sigma value)" ;
> TKE_P0_L104_GLC0:parameter_template_discipline_category_number = 0, 0, 19, 11 
> ;
> TKE_P0_L104_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Physical atmospheric properties" ;
> TKE_P0_L104_GLC0:grid_mapping = "Lambert_Conformal" ;
> TKE_P0_L104_GLC0:coordinates = "lat lon" ;
> TKE_P0_L104_GLC0:_FillValue = 1.e+20f ;
> TKE_P0_L104_GLC0:units = "J kg-1" ;
> TKE_P0_L104_GLC0:long_name = "Turbulent kinetic energy" ;
> TKE_P0_L104_GLC0:production_status = "Operational products" ;
> TKE_P0_L104_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float HPBL_P0_L1_GLC0(y, x) ;
> HPBL_P0_L1_GLC0:level = 0.f ;
> HPBL_P0_L1_GLC0:level_type = "Ground or water surface" ;
> HPBL_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 3, 196 ;
> HPBL_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological products, 
> Mass" ;
> HPBL_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> HPBL_P0_L1_GLC0:coordinates = "lat lon" ;
> HPBL_P0_L1_GLC0:_FillValue = 1.e+20f ;
> HPBL_P0_L1_GLC0:units = "m" ;
> HPBL_P0_L1_GLC0:long_name = "Planetary Boundary Layer Height" ;
> HPBL_P0_L1_GLC0:production_status = "Operational products" ;
> HPBL_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float HGT_P0_L1_GLC0(y, x) ;
> HGT_P0_L1_GLC0:level = 0.f ;
> HGT_P0_L1_GLC0:level_type = "Ground or water surface" ;
> HGT_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 3, 5 ;
> HGT_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological products, 
> Mass" ;
> HGT_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> HGT_P0_L1_GLC0:coordinates = "lat lon" ;
> HGT_P0_L1_GLC0:_FillValue = 1.e+20f ;
> HGT_P0_L1_GLC0:units = "gpm" ;
> HGT_P0_L1_GLC0:long_name = "Geopotential height" ;
> HGT_P0_L1_GLC0:production_status = "Operational products" ;
> HGT_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float HGT_P0_L7_GLC0(y, x) ;
> HGT_P0_L7_GLC0:level = 0.f ;
> HGT_P0_L7_GLC0:level_type = "Tropopause" ;
> HGT_P0_L7_GLC0:parameter_template_discipline_category_number = 0, 0, 3, 5 ;
> HGT_P0_L7_GLC0:parameter_discipline_and_category = "Meteorological products, 
> Mass" ;
> HGT_P0_L7_GLC0:grid_mapping = "Lambert_Conformal" ;
> HGT_P0_L7_GLC0:coordinates = "lat lon" ;
> HGT_P0_L7_GLC0:_FillValue = 1.e+20f ;
> HGT_P0_L7_GLC0:units = "gpm" ;
> HGT_P0_L7_GLC0:long_name = "Geopotential height" ;
> HGT_P0_L7_GLC0:production_status = "Operational products" ;
> HGT_P0_L7_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float SHTFL_P0_L1_GLC0(y, x) ;
> SHTFL_P0_L1_GLC0:level = 0.f ;
> SHTFL_P0_L1_GLC0:level_type = "Ground or water surface" ;
> SHTFL_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 0, 11 ;
> SHTFL_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Temperature" ;
> SHTFL_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> SHTFL_P0_L1_GLC0:coordinates = "lat lon" ;
> SHTFL_P0_L1_GLC0:_FillValue = 1.e+20f ;
> SHTFL_P0_L1_GLC0:units = "W m-2" ;
> SHTFL_P0_L1_GLC0:long_name = "Sensible heat net flux" ;
> SHTFL_P0_L1_GLC0:production_status = "Operational products" ;
> SHTFL_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float LHTFL_P0_L1_GLC0(y, x) ;
> LHTFL_P0_L1_GLC0:level = 0.f ;
> LHTFL_P0_L1_GLC0:level_type = "Ground or water surface" ;
> LHTFL_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 0, 10 ;
> LHTFL_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Temperature" ;
> LHTFL_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> LHTFL_P0_L1_GLC0:coordinates = "lat lon" ;
> LHTFL_P0_L1_GLC0:_FillValue = 1.e+20f ;
> LHTFL_P0_L1_GLC0:units = "W m-2" ;
> LHTFL_P0_L1_GLC0:long_name = "Latent heat net flux" ;
> LHTFL_P0_L1_GLC0:production_status = "Operational products" ;
> LHTFL_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float FRICV_P0_L1_GLC0(y, x) ;
> FRICV_P0_L1_GLC0:level = 0.f ;
> FRICV_P0_L1_GLC0:level_type = "Ground or water surface" ;
> FRICV_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 2, 197 
> ;
> FRICV_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological 
> products, Momentum" ;
> FRICV_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> FRICV_P0_L1_GLC0:coordinates = "lat lon" ;
> FRICV_P0_L1_GLC0:_FillValue = 1.e+20f ;
> FRICV_P0_L1_GLC0:units = "m s-1" ;
> FRICV_P0_L1_GLC0:long_name = "Frictional Velocity" ;
> FRICV_P0_L1_GLC0:production_status = "Operational products" ;
> FRICV_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> float GUST_P0_L1_GLC0(y, x) ;
> GUST_P0_L1_GLC0:level = 0.f ;
> GUST_P0_L1_GLC0:level_type = "Ground or water surface" ;
> GUST_P0_L1_GLC0:parameter_template_discipline_category_number = 0, 0, 2, 22 ;
> GUST_P0_L1_GLC0:parameter_discipline_and_category = "Meteorological products, 
> Momentum" ;
> GUST_P0_L1_GLC0:grid_mapping = "Lambert_Conformal" ;
> GUST_P0_L1_GLC0:coordinates = "lat lon" ;
> GUST_P0_L1_GLC0:_FillValue = 1.e+20f ;
> GUST_P0_L1_GLC0:units = "m s-1" ;
> GUST_P0_L1_GLC0:long_name = "Wind speed gust" ;
> GUST_P0_L1_GLC0:production_status = "Operational products" ;
> GUST_P0_L1_GLC0:center = "NOAA Forecast Systems Lab, Boulder CO" ;
> 
> // global attributes:
> :creation_date = "Wed Mar 31 10:53:15 MDT 2010" ;
> :NCL_Version = "5.1.0" ;
> :system = "Linux finch 2.6.26-2-amd64 #1 SMP Tue Jan 12 22:12:20 UTC 2010 
> x86_64 GNU/Linux" ;
> :Conventions = "CF-1.4" ;
> :grib_source = "20100330_i15_f000_WRF-RR.grb2" ;
> :title = "NCL: convert-GRIB-to-netCDF" ;
> }
> 
> 


Ticket Details
===================
Ticket ID: XBG-435230
Department: Support IDV
Priority: Normal
Status: Open