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Hi all:<br>
<br>
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.<br>
<br>
Here's an example. The following is daily measurements from
QUIKSCAT:<br>
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<a class="moz-txt-link-freetext" href="http://apdrc.soest.hawaii.edu:80/dods/public_data/satellite_product/QSCAT/qscat_daily">http://apdrc.soest.hawaii.edu:80/dods/public_data/satellite_product/QSCAT/qscat_daily</a><br>
<br>
The data descriptor file has the following:<br>
TDEF 3776 linear 20JUL1999 1DY<br>
<br>
and the DDS page seems to have the correct values for time:<br>
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<td align="right" valign="top"><b>time</b>:</td>
<td align="left" valign="top">Array of 64 bit Reals [time =
0..3775]
<br>
grads_dim: "t"
<br>
grads_mapping: "linear"
<br>
grads_size: "3776"
<br>
grads_min: "00z20jul1999"
<br>
grads_step: "1dy"
<br>
units: "days since 1-1-1 00:00:0.0"
<br>
long_name: "time"
<br>
minimum: "00z20jul1999"
<br>
maximum: "00z19nov2009"
<br>
resolution: 1.0
</td>
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<br>
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.<br>
<br>
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,<br>
<br>
Jim<br>
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