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<br />excluded because they may not have provided truly independent information. This was a <br /> <br />common occurrence with the UDFCD gauges that were concentrated"in a small region near <br /> <br />metropolitan Denver and thus sampled only a very limited area of the total rainfall system. Any <br /> <br />gauges that did not report consistently at frequencies better than or equal to about once per hour <br /> <br />were also excluded from use in automated gauge-radar adjustment. The PPS Adjustment <br /> <br />algorithm would not be able to determine hourly incremental rainfall accumulations for these <br /> <br />gauges, thus making them useless for real-time calibration purposes. The top 50 gauges from the <br /> <br />resulting list were chosen for use in automated gauge-radar adjustment. All 145 available gauges <br /> <br />were retained for use in scatter plot comparisons of gauge and radar rainfall, however. <br /> <br />4. Performance of the gauge-radar adjustment algorithm <br /> <br /> <br />The FTG WSR-88D radar was not being supplied with real-time rain gauge at the time of <br /> <br /> <br />the flash flood. However, the PPS has been rerun using Archive II radar data and the archived <br /> <br /> <br />rain gauge data described above in a simulated real-time mode. The gauge reports are assumed to <br /> <br />have been received at the WSR-88D within 50 minutes of their observation time. In the real <br /> <br />operational world, there can be longer delays in transmission of the gauge data from the gauge <br /> <br />platform to the WSR-88D, <br />The Build 9 software version of the PPS was run for this event. Details of the PPS <br /> <br />algorithm and its adaptable parameters are described in Fulton et al. (1998). All PPS adaptable <br /> <br /> <br />parameters were set to the values in use at the FTG WSR-88D at the time of the flood. <br /> <br /> <br />Specifically, a few of the more important PPS parameters include the Z-R equation, Z=300 R", <br /> <br /> <br />and the rain rate threshold (sometimes called the "hail cap" and identified by the PPS adaptable <br /> <br />7 <br />