hi:soil moisture mappin using grads, doubts plz clarify

[smita]

Hi everyone,

  I am smita , and i just joined the grads user group.

  I am using grads for the first time, and i am bit confused regarding using data descriptor file. Can u plz help me with this issue.

  I am workin on  a project which maps brightness values[tb] over required region for Ascending and Descending passes of satellite carrying passive microwave radiometer and as the satellite advances it gathers tb values.

  For the ascending pass[when satellite moves frm south to north] and descending[north to south] we have different btd values.I wrote a program which writes out in binary the required varying latitudes,longitudes ,Tbs  values accordingly.

  lat                 lon               btd
  37.820000   97.650002   250.000000
37.040001   93.779999   253.990005
36.709999   95.540001   254.320007 ----- values in asci
  -7.450000   6.810000   155.949997
-7.760000   5.370000   320.000000
  -9.310000   -1.820000   320.000000

  I dont have any Time or Scale value preferences.Only 1 variable needs to be mapped thts Btd takin into account lat and longitude variations.

  Can u plz help me out with how to write the data descriptor file
  sample thing i wrote is

    DSET output.txt
  TITLE Sample Data Set
  UNDEF -9.99E33
  XDEF 100 LINEAR 1 1
  YDEF 100 LINEAR 1 1
  ZDEF 1 LINEAR 1 1
  TDEF 1 LINEAR 1JAN2000 1DY
  VARS 1
  btd 0 99 brightness value
  ENDVARS


  My doubts

  1. When i am giving it as btd it says undefined variable.How do i make it read btd values frm the binary file.

  2. Is the lat and longitude mapping accordin to the output.txt i am givin or, just taking range of lat and long values as mentioned by xdef and ydef.

  Plz tell me how i shuld write my data descriptor file.

  thnk u

  regards
  smitha





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