[gradsusr] Gribmap question

[Becker, Bernd]

Hi,

how can I write a .ctl file for grib data,
describing an average over a period of days starting at a 
certain distance from the initial data time?

The Grib file contains 3 pieces of date information:
time, the forecast run was initialized
start time 
end time of averaging period

for each grib field in the file. The file contains 4 monthly means:

initial time: 20100622
start time  : 20100701
end   time  : 30 days later (20100731)

initial time: 20100622
start time  : 20100801
end   time  : 30 days later (20100831)

initial time: 20100622
start time  : 20100901
end   time  : 29 days later (20100930)

initial time: 20100622
start time  : 20101001
end   time  : 30 days later (20101031)

tdef in ctl file :
tdef 4  linear 00Z01Jul2010 1mo

This does not work.

I tried gribmap with:
-t0
-fnnn
to no avail
and need some input from you. 

Many thanks!
Bernd.

--
Bernd Becker   Climate Impacts Product Development
Met Office Hadley Centre    FitzRoy Road  Exeter   Devon EX1 3PB  United
Kingdom
Tel.: +44 (0) 1392 884511 Fax: +44 (0)870 900 5050
E-mail:bernd.becker at metoffice.gov.uk -  http://www.metoffice.gov.uk