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How do I configure LAS to display a single time series when my data is broken up into several individual 'snapshot' files?
In many instances, data files exist as 'snapshots' covering a single time point or perhaps one year's worth of data. You would like to present these data as a single continuous time series in LAS and allow users to extract time series covering the entire time domain. This can be accomplished with Ferret 'descriptor' (or .des) files. For more documentation on descriptor files, see Chapter 10, section 4 of the Ferret documentation: "creating a multi-file netCDF data set".
Some example descriptor files can be found in your LAS installation
Once you have created a descriptor file, my_time_series.des, and verified it with Ferret, you will need to create the xml configuration information for this data file by hand. The addXml.pl program only works with netCDF files and DODS URLs. The xml should simply reference the name implied by the descriptor file:
<my_time_series url="file:my_time_series" name="My Combined Time Series Data" doc="doc/my_time_series.html"> ... </my_time_series>
1) You can use DODS URLs in a descriptor file as shown in some of the example files.
2) You can get a big head start on creating an xml configuration file by running addXml.pl --out_inc on one of your 'snapshot' files. Then you will only need to modify the time axis to account for the full time series.
3) Descriptor files are currently limited to a maximum of 500 file entries (as of Ferret v5.3).
4) Make sure the descriptor file is located in an appropriate directory referenced by the Ferret environment variable FER_DESCR.
Jonathan Callahan: Jonathan.S.Callahan@noaa.gov
Last modified: May 01, 2003