3. Update the GAGE correction configuration file (Rain1GageCor.conf)
The raingage correction algorithm uses the Rain1GageCor.conf configuration file in
the /usr/sigmet/config directory.
Copy the template in the /usr/sigmet/config_template directory to /usr/
sigmet/config during installation.
The following is an example Rain1GageCor.conf file.
# Rain1GageCor.conf for the Rain1/GAGE correction program
LOG NONE
# OVERRIDE_PRODUCT_NAME JOE
# VERBOSE
MIN_VALID_GAGE 1.00
MIN_VALID_RADAR 1.00
MIN_CORRECTION 0.20
MAX_CORRECTION 5.00
• LOG
Configures where logging information goes to. Choices are NONE, TERM, FILE, or
BOTH. FILE means place in the ${IRIS_LOG}/Rain1GageCor.log file.
• MAX_CORRECTION and MIN_CORRECTION
• The maximum and minimum gage correction factors prevent large, possibly
erroneous corrections from contaminating the data.
The numbers are entered as factors such as 3 and 0.3 for the max and min
respectively.
If the limit is exceeded, the algorithm uses the value of the limit, that is, the
correction factors are saturated at the limit.
• MIN_VALID_GAGE
The minimum amount of rainfall hourly accumulation for a gage to be considered as
having a valid amount of rainfall.
This depends to some extent on the accuracy of the gages. A value of 3 mm (0.12 in)
would be typical. Note that this corresponds to approximately a one hour average
reflectivity factor of 21 dBZ.
• MIN_VALID_RADAR
The minimum RAIN1 accumulation, averaged about a gage that is valid.
Radar precipitation accumulations less than this are considered invalid and no gage
correction is calculated. This is similar to the Minimum Valid Gage Accumulation,
except that in this case it is for the radar. A value of 3 mm (0.12 in) would be typical.
• MIN_VALID_COVERAGE
When the radar RAIN1 pixels about a gage are averaged (1, 9, 25, 49 pixels, and
similar) to make a gage correction, not all of the pixels are generally valid.
If the percentage of valid pixels is less than this value, than a gage correction is not
calculated. For example, if the Minimum Percentage is set to 50 %, and averaging
about a gage is over 3 × 3 pixels, then at least 5 pixels must be valid for a gage
correction to be generated.
• OVERRIDE_PRODUCT_NAME
Use this command if you wish to change the product name of the RAIN1 product.
• RADAR_AVERAGE
Appendix E – Hydromet Raingage Correction
RESTRICTED 369
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