2. In Data : Display, select one of the following:
• dBT Height
• dBZ Height
• dBZc Height
3. In Max Range, select the maximum range for the product.
4. In dBZ Minimum, select the smallest maximum reflectivity for which to show height.
5. Apply the AZ/EL Smoother.
Because of the quantization of the heights by the elevation steps in the volume scan,
you may want to try a longer smoother than you would typically use to help smooth
over the quantization (for example, 3.0 km (1.9 mi)).
More information
‣
Display Parameters (page 27)
‣
Product Parameters (page 23)
‣
Associating Products with Tasks (page 17)
3.8 LAYER: Layer Average
LAYER can compute layer averages of any polar data types in the ingest files.
LAYER can also convert to liquid first and compute VIL Density. When computing VIL
Density, the output is in g/m**3.
The LAYER algorithm is similar to VIL, except that it divides by the layer thickness. The
algorithm process is:
1. Searches out all points in the layer (accounting for earth curvature) over a given range
and at a given azimuth that intercept the PPI scans of the volume scan, including one
point above and below.
2. If the data is Z, it linearizes it.
If the output is VIL density it converts the Z values to W values (W refers to water
content), and averages the values in the layer.
Each data point is assigned a weighting corresponding to the height interval that it
represents in the layer.
3. The result is an intermediate PPI product that is transformed to a Cartesian product and
stored.
4. If Z is selected as the product data parameter, but at run time only T is available (or vice
versa), the product runs with the available data parameter.
LAYER can function when only one angle is in the task, but for best results, this is not
recommended . If no angle in the associated task passes through the layer, no result can be
calculated.
For a layer of 5 ... 10 km (3.1 ... 6.2 mi), in the volume scan example in the following figure,
layer averages cannot be calculated for ranges less than 5 km (3.1 mi). In the resulting
product display, there would be an inner circle of an unscanned area.
Chapter 3 – Configuring IRIS Products
RESTRICTED 41
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