PROGRAM MIDAS_to_obs

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$Id: MIDAS_to_obs.html 6341 2013-07-31 14:24:51Z nancy $

DATA SOURCES / PROGRAMS / NAMELIST / REFERENCES / ERRORS / PLANS / TERMS OF USE

Overview

MIDAS netCDF File to DART observation converter

Alex Chartier (University of Bath, UK) is the point-of-contact for this effort.

"MIDAS runs in Matlab. The raw observations come from GPS receivers as RINEX files, but we can't use them directly just yet ... Currently, the 'slant' (satellite-to-receiver path) observations are inverted by MIDAS to make vertical, column-integrated 'observations' of plasma density."
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DATA SOURCES

Contact Alex for MIDAS observations.

Alex writes out netCDF files that may be converted to DART observation sequence files. The netCDF files have a pretty simple format.

netcdf Test {
dimensions:
        latitude = 5 ;
        longitude = 6 ;
        height = 30 ;
        time = UNLIMITED ; // (1 currently)
variables:
        double latitude(latitude) ;
                latitude:units = "degrees_north" ;
                latitude:long_name = "latitude" ;
                latitude:standard_name = "latitude" ;
        double longitude(longitude) ;
                longitude:units = "degrees_east" ;
                longitude:long_name = "longitude" ;
                longitude:standard_name = "longitude" ;
        double height(height) ;
                height:units = "metres" ;
                height:long_name = "height" ;
                height:standard_name = "height" ;
        double time(time) ;
                time:units = "Days since 1601-01-01" ;
                time:long_name = "Time (UT)" ;
                time:standard_name = "Time" ;
        double Ne(height, latitude, longitude) ;
                Ne:grid_mapping = "standard" ;
                Ne:units = "1E11 e/m^3" ;
                Ne:long_name = "electron density" ;
                Ne:coordinates = "latitude longitude" ;
        double TEC(time, latitude, longitude) ;
                TEC:grid_mapping = "standard" ;
                TEC:units = "1E16 e/m^2" ;
                TEC:long_name = "total electron content" ;
                TEC:coordinates = "latitude longitude" ;
        double Variance(time, latitude, longitude) ;
                Variance:grid_mapping = "standard" ;
                Variance:units = "1E16 e/m^2" ;
                Variance:long_name = "Variance of total electron content" ;
                Variance:coordinates = "latitude longitude" ;
                Variance:standard_name = "TEC variance" ;
// global attributes:
                :Conventions = "CF-1.5" ;
}
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PROGRAMS

The MIDAS_to_obs.f90 file is the source code for the main converter program.

To compile and test, go into the MIDAS/work subdirectory and run the quickbuild.csh script to build the converter and a couple of general purpose utilities. The obs_sequence_tool manipulates (i.e. combines, subsets) DART observation files once they have been created. The default observations supported are those defined in DART/obs_def/obs_def_upper_atm_mod.f90. If you need additional observation types, you will have to add the appropriate obs_def_XXX_mod.f90 file to the input.nml &preprocess_nml:input_files variable and run quickbuild.csh again. It rebuilds the table of supported observation types before compiling the source code.

 

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NAMELIST

This namelist is read from the file input.nml. Namelists start with an ampersand '&' and terminate with a slash '/'. Character strings that contain a '/' must be enclosed in quotes to prevent them from prematurely terminating the namelist.

&MIDAS_to_obs_nml
   input_file    = 'infile.nc'
   obs_out_file  = 'obs_seq.out',
   verbose       = .false.
   /
Item Type Description
input_file character(len=256) Name of the input netCDF MIDAS file to read.
obs_out_file character(len=256) Name of the output observation sequence file that is created.
verbose logical Controls how much informational output is printed during a conversion. .true. the most amount of output. .false. the least amount of output.

Example

&MIDAS_to_obs_nml
   input_file    = '../data/Test.nc',
   obs_out_file  = 'obs_seq.out',
   verbose       = .TRUE.,
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References

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KNOWN BUGS

none

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FUTURE PLANS

none

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Terms of Use

DART software - Copyright 2004 - 2013 UCAR.
This open source software is provided by UCAR, "as is",
without charge, subject to all terms of use at
http://www.image.ucar.edu/DAReS/DART/DART_download

Contact: Tim Hoar
Revision: $Revision: 6341 $
Source: $URL: https://svn-dares-dart.cgd.ucar.edu/DART/releases/classic/observations/MIDAS/MIDAS_to_obs.html $
Change Date: $Date: 2013-07-31 08:24:51 -0600 (Wed, 31 Jul 2013) $
Change history:  try "svn log" or "svn diff"