To follow this tutorial you need to obtain the first 10 or 20 time-steps of a Katrina simulation; in the example below, the first 58 hourly time-steps were used. You can obtain that data (in 58 g-zipped files) from ftp://ftp.ucar.edu/vapor/data/Katrina.
You may proceed to the next step of this tutorial once you obtain this data: VAPOR can directly read wrfout files.
However, when visualizing large datasets, you will get better visualization performance if you convert your WRF data to a VAPOR VDC. For that reason the data conversion is provided as an optional exercise in this tutorial. You may proceed immediately to the next topic of this tutorial if you are not interested in learning about VAPOR data conversion at this time.
Starting with VAPOR 2.3, a data conversion application "vdcwizard" is provided with VAPOR.
vdcwizard provides an easy-to-use user interface for specifying input files and constructing a VAPOR VDC from the files.
VAPOR also provides two command-line utilities for converting WRF-ARW datasets, wrfvdfcreate and wrf2vdf; however all of the conversion capabilities of these two utilities are supported in vdcwizard.
wrfvdfcreate scans a sequence of wrf output files, identifying the coordinate extents and latitude/longitude extents, variables, time steps, and other parameters, and creates a VAPOR metadata file (a .vdf file) that describes the entire dataset. The files must be from the same nesting level of a WRF-ARW simulation.
wrf2vdf performs the actual data conversion from the WRF-ARW output format to the VAPOR VDC format. This operation requires reading all the data to be converted and can take several minutes depending on the size of your data.
It may be useful to know the latitude/longitude extents of your WRF data. These extents are displayed in the output of wrfvdfcreate, and are also provide by vdcwizard if you click the "Advanced" button after specifying the wrfout files for creating a vdf file. The following is the vdcwizard Advanced panel with latitude/longitude extents:
Make a note of the latitute/longitude extents of the data. This will be useful later when we obtain a terrain image for this region.
After all the time steps are converted, you will note that, in the same directory where the file Katrina.vdf is stored, there is now a subdirectory, named "Katrina_data", containing many subdirectories and files associated with the VAPOR version of the data.
