[gradsusr] interpolating data to a regular grid

[Zilore Mumba]

Dear Grads Users,
I have station rainfall data which I want to draw contours. I have searched
previous posts on regridding data to a regular grid, but am not sure if the
suggested solutions are relevant to my case, or whether what am trying to
do is possible. When I write the data in binary as longitude, latitude,
value the display is very strange. I can write it as station values and
display as in the file attached.
What I want to be able to do is to interpolate between stations and draw
contours.
My data looks as follows:
01  28.92  -2.47  286.5
02  29.02  -2.68  168.8
03  29.25  -1.67  243.4
04  29.42  -2.07  204.9
05  29.55  -1.58  286.9
06  29.57  -2.48  230.
07  29.6   -1.5   177.5
08  29.72  -2.18  290.
09  30.05  -1.6   206.5
10  30.13  -1.97  178.1
11  30.5   -2.15  156.7
The longitudes are sorted from smallest (western most) to largest, but
obviously it is not possible to sort latitudes.
Below is the ctl I wrote to display the data written as lon, lat value
(without the id number)
DSET      means.grd
TITLE     Sample Data Set
UNDEF    -9.99E33
XDEF     11 LINEAR 28.9 .2
YDEF     11 LINEAR -2.6 .1
ZDEF      1 LINEAR 1 1
TDEF      1 LINEAR 1JAN2000 1DY
VARS      1
r  0  99  rainfall
ENDVARS

Is it possible to do what I want to do?
Help will be appreciated
Zilore
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