qcat and GrADS

[Michael J Murphy]

GRADSUSR list,

   I have downloaded a QSCAT data file in  netcdf format and have been trying to view the data with GrADS by creating a .ddf (data descriptor file) along with using the xdfopen command.  I have read though all the GrADS documentation and have been unsuccessful in converting the dimensions of the data into a format that GrADS can read.

  I have added the contents of an ncdump command I did on the file at the end of this email.  As you can see the only dimensions specified are time and cross_track cells.  I understand how the file is divided up into swaths with a variable for latitude and longitude for each swath.  What I don't understand is how to put this convention into a .ddf format that GrADS can read.

  I emailed the people who supply the data and they said I should be able to open the file by using a sdfopen command.  This has not worked however because the .nc file does not appear to be in COARDS format (I get an error message about there being no discerable X coordinate).  Any advice someone might have with this issue will be greatly appreciated.

Thanks,
MJ


    

> ncdump -c QSCAT.2006092.nc
netcdf QSCAT.2006092 {
dimensions:
        time = UNLIMITED ; // (23157 currently)
        cross_track_cells = 76 ;

variables:
        long Row_Mean_Time(time) ;
                Row_Mean_Time:long_name = "average time" ;
                Row_Mean_Time:units = "seconds from 1-1-1999 00:00:00" ;
                Row_Mean_Time:actual_range = 228787201, 228873597 ;
                Row_Mean_Time:scale_factor = 1 ;
                Row_Mean_Time:add_offset = 0 ;
                Row_Mean_Time:missing_value = 0 ;
        short WVC_lon(time, cross_track_cells) ;
                WVC_lon:long_name = "longitude" ;
                WVC_lon:units = "degrees" ;
                WVC_lon:actual_range = 0.f, 359.98999f ;
                WVC_lon:scale_factor = 0.0099999998f ;
                WVC_lon:add_offset = 180.f ;
                WVC_lon:missing_value = 32767s ;
        short WVC_lat(time, cross_track_cells) ;
                WVC_lat:long_name = "latitude" ;
                WVC_lat:units = "degrees" ;
                WVC_lat:actual_range = -73.68f, 79.919998f ;
                WVC_lat:scale_factor = 0.0099999998f ;
                WVC_lat:add_offset = 0.f ;
                WVC_lat:missing_value = 32767s ;
        short Wind_Dir(time, cross_track_cells) ;
                Wind_Dir:long_name = "wind direction" ;
                Wind_Dir:units = "degrees (oceanic convention)" ;
                Wind_Dir:actual_range = 0.f, 360.f ;
                Wind_Dir:scale_factor = 0.0099999998f ;
                Wind_Dir:add_offset = 180.f ;
                Wind_Dir:missing_value = 32767s ;
        short Wind_Speed(time, cross_track_cells) ;
                Wind_Speed:long_name = "wind speed" ;
                Wind_Speed:units = "m/s" ;
                Wind_Speed:actual_range = 0.f, 69.f ;
                Wind_Speed:scale_factor = 0.0099999998f ;
                Wind_Speed:add_offset = 0.f ;
                Wind_Speed:missing_value = 32767s ;
        byte Rain_Flag_combination(time, cross_track_cells) ;
                Rain_Flag_combination:long_name = "rain flag" ;
                Rain_Flag_combination:units = "none" ;
                Rain_Flag_combination:actual_range = 0s, 1s ;
                Rain_Flag_combination:scale_factor = 1.f ;
                Rain_Flag_combination:add_offset = 0.f ;
                Rain_Flag_combination:missing_value = 255s ;
                Rain_Flag_combination:rain_threshold = 1s ;
        byte Rain_Flag_rad(time, cross_track_cells) ;
                Rain_Flag_rad:long_name = "radiometer rain flag" ;
                Rain_Flag_rad:units = "none" ;
                Rain_Flag_rad:actual_range = 0s, 1s ;
                Rain_Flag_rad:scale_factor = 1.f ;
                Rain_Flag_rad:add_offset = 0.f ;
                Rain_Flag_rad:missing_value = 255s ;
                Rain_Flag_rad:rain_threshold = 1s ;

// global attributes:
                :build_id = "2.3.2/2000-04-07" ;
                :Model_function = "Ku-2001" ;
                :sensor_name = "SeaWinds on QuikSCAT" ;
                :first_data_time = "02 April 2006 00:00:01" ;
                :last_data_time = "02 April 2006 23:59:57" ;
                :wind_reference_height = "10m" ;
                :history = "Created on 04 April 2006 by COAPS/FSU" ;
                :contact_info = "scat_sci at coaps.fsu.edu" ;

data:
}


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