Vaisala IRIS - RAIN1 Scheduling with GAGE Product

2. Gage Correction Interpolation for Each Pixel
The gage correction factors are then applied to the uncorrected RAIN1 product to yield
the final corrected RAIN1 output product. The technique is that the rainfall
accumulation value at each pixel in the uncorrected RAIN1 product is multiplied by an
average correction factor.
The average correction factor for a pixel is calculated from all gages by weighting the
correction factor for each gage inversely with its distance from the pixel, that is,
C
−
+
Σ
C
i
D
i
Σ
1
D
i
where
C
−
is the average gage correction for a pixel,
C
i
is the correction at a gage and
D
i
is the distance between the gage and the pixel. Note that the minimum value of
D
i
is
fixed at 1 km (0.6 mi).
E.6 RAIN1 Scheduling with GAGE
Product
The scheduling algorithm for generation of the RAIN1 product is dierent from the standard
RAIN1 scheduling since the product generator must await the arrival of both the CAPPIs and
the GAGE product for the previous hour. To account for the delay in the arrival of the GAGE
product, a Gage Wait Time is defined in IRIS Setup > Product. In the following figures, this is
labelled WaitG.
The notation shows a time line which represents the data time, that is, in the case of a
CAPPI, this is the time that the volume scan was started based on the clock on the radar
computer which may be dierent than the clock on the computer where RAIN1 is generated.
In the case of a GAGE product this is the time exactly on the hour, at the end of the
accumulation hour. Vertical bars show even hours.
Case 1A: Normal Case, CAPPIs and GAGE Arrive
CC C C CC C C
G
This is the normal case when both the CAPPI and the GAGE products arrive. The GAGE
product arrives sometime after the hour, but in Data Time it is plotted exactly on the hour.
The RAIN1 product is run as soon as the GAGE product arrives and the first CAPPI from the
next hour arrives.
IRIS Product and Display User Guide M211319EN-H
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