[thredds] FMRC collections and the regularize=true attribute

• To: THREDDS community <thredds@xxxxxxxxxxxxxxxx>
• Subject: [thredds] FMRC collections and the regularize=true attribute
• From: John Caron <caron@xxxxxxxx>
• Date: Wed, 3 Jun 2015 13:13:23 -0600

FMRC collections allow you to combine multiple model runs into a single
dataset. Our examples often show the use of the regularize attribute, eg:

<fmrcConfig regularize="true" datasetTypes="Files">
  <dataset name="Best" offsetsGreaterEqual="0"/>
</fmrcConfig>

because for the data we serve on thredds.ucar.edu, that is the correct
setting.

However, if you use FMRC collections on data that doesnt actually have 2D
times, you will get incorrect time coordinates. For example, you can use
FMRC on any homogenous collection of Gridded data.

If you use FMRC collections, please review your configurations for correct
use of this attribute. If in doubt, send a note to this list or
support-thredds.

From
http://www.unidata.ucar.edu/software/thredds/v5.0/tds/reference/collections/FmrcCollection.html#fmrcConfig
:

*regularize: If true, then the runs for a given hour (from 0Z) are assumed
to have the same forecast time coordinates. For example, if you have 4
model runs per day (eg 0, 6, 12, 18Z) and many days of model runs, then all
the 6Z runs for all days will have the same time coordiantes, etc. This
"regularizes" time coordinates, and is useful when there may be missing
forecast times, which may result in creating a new time coordinate. *

*Leave this to false unless you really have a series of runs with uniform
offsets.*