The WARN product operates on the color bands in the product image and the
threshold is set accordingly.
For example, to set up a reflectivity warning based on a CAPPI product.
• Display an example of the product.
• Choose your threshold to match the number displayed with the color band that
you want to use as your threshold.
If 45 dBZ is the number displayed with the red color, and you set your threshold to
45 dBZ, then all of the regions displayed as red (or "greater") are included in the
warning algorithm. This is convenient for verifying the algorithm. If you display the
reflectivity product along with the situation display (warning overlay), the centroid
labels are positioned precisely in the red-colored regions.
For the VVP product, the threshold refers to the divergence in units of m/s per km
(10
-3
s
-1
). When the WARN product is run for the VVP, a warning is generated if the
divergence exceeds this value at any height in the VVP. Strong low-level divergence
over the radar could be an indicator of a microburst. To properly set for microburst
alerts, you must know the local characteristics of the phenomena.
6. Under Protected Areas for Warning Alert, select Protected Areas to see a list of areas.
The protected areas are configured in the setup utility. They are constrained to be
rectangles with arbitrary size and orientation angle. There is a limit of 16 areas. (If you
make a change to Setup, you must restart IRIS for the change to take eect.)
It is a good idea to make a large area (for example, 500 by 500 km
(310.7 × 310.7 mi)) named ALL. When ALL is selected, the entire radar area out to
250 km (155.3 mi) range is a protected area.
7. Select TDWR Style to use the TDWR warning message format.
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. These messages are displayed at the bottom of the
display screen and optionally spoken.
8. Select Say/Beep Warning to have the product generator to audibly signal the warning
message in addition to displaying it as a message.
You must also select Enable Speech from the IRIS Setup menu.
9. Select Make Diagnostic for the product generator to create additional diagnostic
output.
The diagnostic is a USER product type, with a USER data type, and the same name as
the WARN product, except for a MSK.
You can display this product in the IRIS Radar Quick-Look Window.
This product contains the output of the initial thresholded input data. The LSB is the
first input, bit 1 is the second, and bit 2 is the third. For a WARN of only one input, expect
a binary file. You can use this to see the regions being processed.
Chapter 3 – Configuring IRIS Products
RESTRICTED 107
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