3. Configure the associated VVP task.
The VVP algorithm performs unfolding of the data. For best results, configure a task
with a large unambiguous velocity range.
That is, use a high PRF (such as 1200 Hz) and dual-PRF velocity unfolding (either 4:3 or
3:2) so that velocity folding does not occur.
If your standard volume scan does not use dual PRF unfolding, you might want to set
up a separate task for the VVP.
Four elevation angles, such as 30, 20, 10, and 5°, are usually adequate because each
angles contribute to many heights.
More information
‣
Associating Products with Tasks (page 17)
3.24.1
Producing VVP Product Output
VVP product output consists of a data file containing the VVP parameters for each height.
The displays are computed on-the-fly from the data file and are customizable. The available
VVP displays in IRIS are:
• Line graphs against height
Up to 5 parameters can be selected for plotting against height. Standard deviation bars
are included on the plots.
• Time-height cross-sections
Wind barbs, wind strings or axis of dilation/deformation lines are superimposed on a
colored background of reflectivity, RhoHV, deformation, divergence or vertical velocity.
Time scale and height are selectable.
You can select the display style, parameters, plot limits, and so on in the Output Options
menu of the Quick Look window or Product Output Menu.
Thresholding in the displays is based on the goodness of fit of the velocity. In Output
Options, you can set the threshold level between 0 (display all data) and 1 (threshold all
data).
More information
‣
VVP Output Options: Line Graphs (page 253)
‣
VVP Output Options: Time-Height (page 251)
3.25
WARN: Warning/Centroid Product
The WARN product uses other IRIS products to detect significant weather.
Chapter 3 – Configuring IRIS Products
RESTRICTED 99
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