[gradsusr] Opening a file having overlapping longitude points.

Martin V. Mathew vmartinmathew at gmail.com
Tue Mar 29 02:22:16 EDT 2011


Hai All

I have a problem in opening an ocean current data in NetCDF format,
downloaded from URL
http://www.oscar.noaa.gov/datadisplay/index.html

It is a 1degree resolution file with 400 longitude points.
It is given in the documentation of the data that

'Longitude extends from 20.5 E to 419.5 E to avoid a break in major ocean
basins.
Data repeats in overlap region.'

Dimensions of the data is as  follows

*****************************************************************************************
        time = 12 ;
        depth = 1 ;
        lat = 120 ;
        lon = 400 ;

 lat = 59.5, 58.5, 57.5, 56.5,.................................

.................................................................................,
-57.5, -58.5, -59.5 ;

 lon = 20.5, 21.5, 22.5, 23.5,.....................
    ..............., 357.5,358.5, 359.5, 360.5, 361.5, 362.5, 363.5, 364.5,
    365.5, 366.5, 367.5, 368.5, 369.5, 370.5, 371.5, 372.5, 373.5, 374.5,
    375.5, 376.5, 377.5, 378.5, 379.5, 380.5, 381.5, 382.5, 383.5, 384.5,
    385.5, 386.5, 387.5, 388.5, 389.5, 390.5, 391.5, 392.5, 393.5, 394.5,
    395.5, 396.5, 397.5, 398.5, 399.5, 400.5, 401.5, 402.5, 403.5, 404.5,
    405.5, 406.5, 407.5, 408.5, 409.5, 410.5, 411.5, 412.5, 413.5, 414.5,
    415.5, 416.5, 417.5, 418.5, 419.5 ;
*****************************************************************************************

While trying to open the file in GrADS using sdfopen following error message
is displayed
------------------------------------------------------------------------------------
Scanning self-describing file:  oscar-4cff2332a2540_1995.nc
gadsdf: SDF file has no discernable X coordinate.
------------------------------------------------------------------------------------

I also tried to open the file using a control file in which I defined
longitude as follows

  DSET oscar-4cff2332a2540_1995.nc
    XDEF lon 400 LEVELS  20.5, 21.5, 22.5, 23.5, .........................

..........................................................................................................................
    .............., 355.5, 356.5, 357.5, 358.5, 359.5,.5,1.5,2.5,
3.5,............

.....................................................................,55.5,56.5,57.5,58.5,59.5


I couldn't open the file using this method also.
While trying to open the file following error message is displayed

------------------------------------------------------------------------------------
ga-> xdfopen oscar-4cff2332a2540_1995.ctl
Scanning Descriptor File:  oscar-4cff2332a2540_1995.ctl
Open Error:  Unexpected EOF reading descriptor file
   EOF occurred reading LEVELS values
  --> The invalid description file record is:
  -->
46.5,47.5,48.5,49.5,50.5,51.5,52.5,53.5,54.5,55.5,56.5,57.5,58.5,59.5

  The data file was not opened.
ga->
------------------------------------------------------------------------------------

Somebody please give me a suggestion to solve this problem.

Thanking you

Martin V. Mathew
J.R.F.
Centre for Oceans, Rivers, Atmosphere and Land Sciences (CORAL)
IIT Kharagpur
India.
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