YOTC data with real_imaginary dimension

From: Matthew Janiga <matthew.janiga_at_nyahnyahspammersnyahnyah>
Date: Fri, 18 Sep 2009 11:20:04 -0400

Greetings,

I am having some trouble with YOTC model data
(http://data-portal.ecmwf.int/data/d/yotc_od/levtype=pl/type=an/).
When I use ncl_filedump on the pv .grib format YOTC data I get normal
lat lon grids. However, the primary variables are packed using
spherical harmonics (I may be phrasing this wrong). These variables
have half the “lon” elements (it isn’t really lon correct?) and an
extra dimension real_imaginary. I saw some old messages pertaining to
this problem but I can’t seem to figure out how to get this into the
same coordinates as the pv.

I’d like to read in these “packed” primary variables and covert them
to the dimensions that pv is in. Any help with this would be greatly
appreciated!

I’ve included the results of ncl_filedump on pv and temperature data below.

Thanks,
Matt (janiga_at_atmos.albany.edu)

Copyright (C) 1995-2009 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 5.1.1
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
Variable: f (file variable)

filename: pv.200807
path: pv.200807.grib
   file global attributes:
   dimensions:
      initial_time0_hours = 124
      lv_ISBL1 = 15
      g4_lat_2 = 800
      g4_lon_3 = 1600
   variables:
      float PV_GDS4_ISBL ( initial_time0_hours, lv_ISBL1, g4_lat_2, g4_lon_3 )
         center : European Center for Medium-Range Weather
Forecasts (RSMC)
         long_name : Potential vorticity
         units : K m**2 kg**-1 s**-1
         _FillValue : 1e+20
         level_indicator : 100
         gds_grid_type : 4
         parameter_table_version : 128
         parameter_number : 60
         forecast_time : 0
         forecast_time_units : hours

      double initial_time0_hours ( initial_time0_hours )
         long_name : initial time
         units : hours since 1800-01-01 00:00

      double initial_time0_encoded ( initial_time0_hours )
         long_name : initial time encoded as double
         units : yyyymmddhh.hh_frac

      float g4_lat_2 ( g4_lat_2 )
         long_name : latitude
         GridType : Gaussian Latitude/Longitude Grid (Quasi-Regular)
         units : degrees_north
         N : 400
         Di : 0.225
         Lo2 : 359.775
         La2 : -89.827
         Lo1 : 0
         La1 : 89.827

      float g4_lon_3 ( g4_lon_3 )
         long_name : longitude
         GridType : Gaussian Latitude/Longitude Grid (Quasi-Regular)
         units : degrees_east
         N : 400
         Di : 0.225
         Lo2 : 359.775
         La2 : -89.827
         Lo1 : 0
         La1 : 89.827

      integer lv_ISBL1 ( lv_ISBL1 )
         long_name : isobaric level
         units : hPa

      string initial_time0 ( initial_time0_hours )
         long_name : Initial time of first record
         units : mm/dd/yyyy (hh:mm)

Copyright (C) 1995-2009 - All Rights Reserved
 University Corporation for Atmospheric Research
 NCAR Command Language Version 5.1.1
 The use of this software is governed by a License Agreement.
 See http://www.ncl.ucar.edu/ for more details.
Variable: f (file variable)

filename: t.200807
path: t.200807.grib
   file global attributes:
   dimensions:
      initial_time0_hours = 124
      lv_ISBL1 = 15
      real_imaginary = 2
      g50_lat_3 = 800
      g50_lon_4 = 800
   variables:
      float T_GDS50_ISBL ( initial_time0_hours, lv_ISBL1,
real_imaginary, g50_lat_3, g50_lon_4 )
         center : European Center for Medium-Range Weather
Forecasts (RSMC)
         long_name : Temperature
         units : K
         _FillValue : 1e+20
         level_indicator : 100
         gds_grid_type : 50
         parameter_table_version : 128
         parameter_number : 130
         forecast_time : 0
         forecast_time_units : hours

      double initial_time0_hours ( initial_time0_hours )
         long_name : initial time
         units : hours since 1800-01-01 00:00

      double initial_time0_encoded ( initial_time0_hours )
         long_name : initial time encoded as double
         units : yyyymmddhh.hh_frac

      integer lv_ISBL1 ( lv_ISBL1 )
         long_name : isobaric level
         units : hPa

      string initial_time0 ( initial_time0_hours )
         long_name : Initial time of first record
         units : mm/dd/yyyy (hh:mm)

-- 
**********************************
Matthew A. Janiga
Department of Earth and Atmospheric Sciences, ES 330
University at Albany / State University of New York
1400 Washington Avenue
Albany, NY 12222
PH: (847) 962-8397
Email: janiga_at_atmos.albany.edu
**********************************
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Received on Fri Sep 18 2009 - 09:20:04 MDT

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