[gradsusr] Problem with GrADS in reading ECMWF synoptic monthly means data

[Arlindo da Silva]

On Sun, Sep 18, 2011 at 2:39 PM, Mubashar Dogar <mubashardogar at gmail.com>wrote:

>
> Dear GrADS users,
>
> I am facing a problem with time steps of a netcdf file downloaded for
> synoptic monthly means of ECMWF ERA-INTERIM forecast product for the year
> 1989 (downloaded for surface total precipitation for all time steps
> available from: http://data-portal.ecmwf.int/data/d/interim_mnth/). This
> file is basically synoptic monthly means generated by long term average of
> corresponding 3 hour in all the days of a month, giving 8 time steps in a
> month. So instead of reading 96 values that represents to 12 months (8
> values in each months) GrADS read all these values by considering 8 time
> steps in a day instead in a month. I mean GrADS reads these hours in a daily
> format instead of monthly. Does GrADS not deal with synoptic monthly means?
> I have grib file as well for the same data, what should be time increment in
> a ctl file to open the same grib file?
>
>
One strategy is to use the ensemble dimension to deal with the fact that you
have 2 time scales involved. For example, you you associate each month with
the grads time dimension and each "time of the day" with the grads ensemble
dimension. (Or you can swap these if you prefer.) This recipe discusses how
this can be done for the MERRA monthly diurnal files.

http://cookbooks.opengrads.org/index.php?title=Recipe-024:_Using_the_Ensemble_Dimension_with_Monthly_Mean_Diurnal_files_from_MERRA

    Arlindo









>
> Mubashar Dogar
>
>
>
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>


-- 
Arlindo da Silva
dasilva at alum.mit.edu
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