E.4 Configuring RAIN1 with Raingage
Correction
1. Configure the input CAPPI products.
The RAIN1 algorithm starts with CAPPI products. See CAPPI : Constant Altitude Plan
Position Indicator (page 36).
To optimize the CAPPI products for RAIN1 with GAGE correction, consider the
following:
• CAPPI data type set to R based on Z.
The input CAPPI should be made in rainfall rate units. This causes the CAPPI
interpolation to be done on rainfall rate rather than on dBZ. Thus the weighting of
the interpolation is linear in rainfall rate units.
Use the corrected reflectivity factor Z instead of the uncorrected reflectivity factor T
so that you can benefit from clutter correction and cancelation.
• CAPPI resolution of approximately 1 km (0.6 mi)
The resolution of the RAIN1 product is identical to that of the input CAPPI product.
Vaisala recommends that the maximum range for the CAPPI and the number of
pixels be set to yield a resolution of approximately 1 km (0.6 mi). For example, for a
240 maximum range, a 480 × 480 product would have 1 km (0.6 mi) resolution.
• CAPPI height of approximately 1 km (0.6 mi), Fill set to Yes (Pseudo CAPPI)
Select a single-level CAPPI height of approximately 1 km depending on the height of
the surrounding terrain. Note that CAPPI heights are defined as height above a
reference level that is usually set to sea level (in IRIS Setup/RCP). Enable the CAPPI
Fill so that the CAPPI is defined for near and far ranges where it is not possible to
interpolate to 1 km.
• Use default Z-R relationship of Z=200R
1.6
Vaisala recommends that you initially use a default Z=200R
1.6
as the default Z-R
relationship in the CAPPI product. After some experience, you may choose to
modify this to match their precipitation more closely. This relationship can be
adjusted seasonally as well.
2. Configure the RAIN1 product.
For the RAIN1 product configuration select the input CAPPIs configured above. Use the
same Z-R relationship in the RAIN1 product as was used for the CAPPIs.
If you want to use gage correction, select the gage correction button.
IRIS Product and Display User Guide M211319EN-H
368 RESTRICTED
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