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CBRFC Issues 1st Q2 workshop 28-30 June 2005. Craig Peterson Greg Smith Colorado Basin RFC Salt Lake City, Utah. Precipitation quality control. Colorado, Wyoming, Central/Nrn Utah daily_qc 6/24 hour Gage only Quality control temperature and freezing level
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CBRFC Issues1st Q2 workshop 28-30 June 2005 Craig Peterson Greg Smith Colorado Basin RFC Salt Lake City, Utah
Precipitation quality control • Colorado, Wyoming, Central/Nrn Utah • daily_qc • 6/24 hour • Gage only • Quality control temperature and freezing level • Outputs include points, grids and MAPs • Arizona, New Mexico, Southern Utah • MPE • “Front ended” by daily_qc • 1 hour • Mixture of gage and radar • Satellite estimates can be used in data void areas • Outputs include points and grids
Operational use of MPE • Seasonal variation • Winter primarily gage only • Summer mixture of gage and radar
CBRFC Operational Issues • Hourly gages often “front ended” by daily_qc • Has various tools to help QC gage data • Defining usable NEXRAD area • Defines NEXRAD mask so that areas under radar umbrella with low confidence are “blocked” out • Helps greatly in calculating the bias adjustment
Defining usable NEXRAD area-Current method Statically define radar coverage field Hybrid scan, Occultation Elevation assumption Use if mid point elevation of beam: Summer < 20000 ft Winter (liquid events only!) < 6000 ft north of 37N < 12000 ft south of 37N Maximum 30 percent blockage Agrees well with radar climatology (summer)
Defining usable NEXRAD-Future Requirements • Dynamically define radar coverage field • Hybrid scan, Occutlation • Freezing/melt level (hourly) • Only use liquid events • Elevation assumption • Specific to event? • Define hourly
Other CBRFC Issues • Satellite estimates have been used in data void areas • Short term QPF needed for 1 hourly segments especially for convective events in smaller basins • Bias adjustments • Consistent Z-R relationships