Vaisala IRIS - Shear Line Radar Signatures

10. Configure SLINE for use with warnings.
Protected Areas for Warning Alert
Specify one or more protected areas. A warning is generated if a shear line is
within a protected area or is forecast to move into one.
Select Protected Areas to see a list of areas and toggle a choice on or o. When
you exit the list, the names of the selected areas are displayed in the field.
Protected areas are configured with the Setup utility. They are constrained to be
rectangles with arbitrary size and orientation angle. Up to 32 areas can be
configured.
If you make a change to Setup, you must restart IRIS for the change to take
eect. See IRIS and RDA Utilities Guide.
TDWR Style
IRIS supports two formats of warning messages.
In TDWR format, only the strongest centroid in the highest priority area is
reported along with its strength. For example: MBA 3MF 30K–, in spoken
language: Microburst Alert, Three Mile Final, 30 Knot loss.
The older IRIS format reports all centroids in all protected areas, for example: 3
MBA warnings at 11:30 in: 3MF, 2MF.
The messages are displayed at the bottom of the display screen, and optionally
spoken.
Say Warning
When enabled, the product generator to audibly signals the warning message in
addition to displaying it as a message.
You must also select Setup > Enable Speech in IRIS.
11. To troubleshoot or test SLINE products, enable a thresholded version of the input
SLINE product by selecting Make Diagnostic Results.
This has the same product name as the SLINE.
More information
‣
Display Parameters (page 27)
‣
Associating Products with Tasks (page 17)
‣
Product Parameters (page 23)
5.7.1
Shear Line Radar Signatures
Detection of shear lines is based on the Doppler velocity rather than the reflectivity.
However, accurate measurement of the Doppler velocity requires sucient returned power.
The radar reflectivity associated with shear lines can be from precipitation or clear air
echoes. Because clear air echoes tend to be weak, the most ecient detection requires that
the radar scan slowly for sucient averaging.
The climatology of shear lines for a particular location dictates the scan strategy. If shear
lines tend to be associated with weak returns, a slow scan rate is necessary for reliable
detection. The trade-o between reliable detection of weak echo features and the need for
rapid updates to detect phenomena such as microbursts is a decision that you must make,
based on your site and application.
Chapter 5 – Configuring and Scheduling Optional IRIS Products
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