[gradsusr] GDS date-time standard

[maria elena bravo gasca]

Hi!!!!   sorry!

you know how to unzip the *. RT?
the RT files are GRIB files?
this files are from NOAA CPC

appreciate your help!

i am from mexico and is the first time that i use the program Grads

mary.



2013/10/7 James T. Potemra <jimp at hawaii.edu>

>  Hi all:
>
> I'm wondering if anyone knows how GDS derives a date-time value from a
> GrADS style binary file?  For example, a contributed data set could have a
> descriptor file with a TDEF defining a start-date of Jan 1, 2013 and
> increment of 1dy.  If this file were served via GDS, the OPeNDAP date-time
> becomes "days-since-1-1-1".  In experimenting with some GDS-served files,
> it seems that this conversion is off by two days.
>
> Here's an example.  The following is daily measurements from QUIKSCAT:
>
> http://apdrc.soest.hawaii.edu:80/dods/public_data/satellite_product/QSCAT/qscat_daily
>
> The data descriptor file has the following:
> TDEF 3776  linear  20JUL1999  1DY
>
> and the DDS page seems to have the correct values for time:
>   *time*: Array of 64 bit Reals [time = 0..3775]
> grads_dim: "t"
> grads_mapping: "linear"
> grads_size: "3776"
> grads_min: "00z20jul1999"
> grads_step: "1dy"
> units: "days since 1-1-1 00:00:0.0"
> long_name: "time"
> minimum: "00z20jul1999"
> maximum: "00z19nov2009"
> resolution: 1.0
> However, the OPeNDAP supplied first time-step is 729956 (obtained either
> through python call or ncdump).  I think that this corresponds to July 22,
> 1999 rather than the actual July 20, 1999 as defined in the descriptor file.
>
> Can anyone comment on what's going on here?  I found the same behavior
> with two other daily files, same apparent 2-day off-set.  Thanks,
>
> Jim
>
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