[gradsusr] GTOPO30

[Clark, Douglas B.]

Dibas,

I just noticed that the error message mentions "location 14400000", which I think is just beyond the half-way point of the data set.
So perhaps you have 16-byte data, not the 32-byte data that I and your ctl file assumed.

See the GrADS documentation http://grads.iges.org/grads/gadoc/gadocindex.html 
> control file
> vars
for how to deal with other types of data.

Doug


-----Original Message-----
From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Clark, Douglas B.
Sent: 07 October 2011 11:52
To: Dibas Shrestha; GrADS Users Forum
Subject: Re: [gradsusr] GTOPO30

Dibas,

It might be that your data file (E060N40.DEM) doesn't contain enough data.
How large is it?
Your ctl file suggests that the file would be 4800 x 6000 x 4 bytes per value = 115 200 000 B.
If it isn't, the ctl file isn't correct.

I also notice that you have "TDEF 48", which is slightly unexpected for topographic data - don't you just have one time level? If so, "tdef 1" is correct. 

Doug



From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Dibas Shrestha
Sent: 07 October 2011 11:39
To: gradsusr at gradsusr.org
Subject: [gradsusr] GTOPO30

Hi all 

I have downloaded e060n40 elevation data and converted to E060N40.DEM. 
Then tried to use grads with following control file,
DSET ^E060N40.DEM 
TITLE topography data
UNDEF -9999
OPTIONS little_endian
XDEF 4800  LINEAR   60     0.00833333333333
YDEF 6000  LINEAR   -10    0.00833333333333
ZDEF 1    LEVELS 0 
TDEF  48    Linear 26jun2001 06hr
VARS    1
topo    0       1       height [meter]
ENDVARS

But the following error is occured,

ga-> d topo
Low Level I/O Error:  Read error on data file 
  Data file name = E060N40.DEM 
  Error reading 4800 bytes at location 14400000 
Data Request Error:  Error for variable 'topo'
  Error ocurred at column 1
DISPLAY error:  Invalid expression 
  Expression = topo

Could anyone suggest me!!!!

Thanking in advance
Dibas
HyARC,
Nagoya University
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