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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Table 2. - Summary of storm total SWE accumulations (mm), using both Level II and Level III <br />reflectivity data as input to the SAA, for five different Minnesota winter storms. Ratios of Level III <br />to Level II are also listed. Start times of each storm period are given in UTe time by YYMMDDHH. <br /> 96112022 96122222 97010420 97022818 97030321 <br />4 to 230 k.m: Level II 2.17 2.92 2.34 2.42 2.49 <br />Level III 2.19 3.28 2.47 2.63 2.65 <br />Ratio: III / II 1.01 1.12 1.06 1.09 1.06 <br />4 to 75 k.m: Level II 4.57 8.41 4.93 4.63 6.41 <br />Level III 4.42 8.74 5.07 4.67 6.34 <br />Ratio: III/II 0.97 1.04 1.03 1.01 0.99 <br />76 to 150 k.m: Level II 3.13 4.75 3.51 3.65 3.75 <br />Level III 3.11 5.31 3.63 3.87 3.98 <br />Ratio: III/II 0.99 1.12 1.03 1.06 1.06 <br />151 to 230 k.m: Level II 1.18 0.88 1.21 1.33 1.06 <br />Level III 1.26 1.13 1.33 1.56 1.23 <br />Ratio: III / II 1.07 1.28 1.10 1.17 1.16 <br />4 to 150 k.m: Level II 3.49 5.67 3.87 3.90 4.42 <br />Level III 3.44 6.17 3.99 4.07 4.57 <br />Ratio: III/II 0.99 1.09 1.03 1.04 1.03 <br /> <br />Considering the higher resolution Level II data runs to be the "standard," the ratios <br />in table 2 show that Level III runs for the entire area of radar coverage are greater <br />by values from 1 to 12 percent. Agreement is better for the 75 km closest to the <br />radar, with Level III values ranging from 3 percent less to 4 percent more. For the <br />76- through 150-km range interval, Level III values are from 1 percent less to 12 <br />percent more. For the combined 150 km closest to the radar, where SAA <br />performance is expected to be best, Level III estimates range from 1 percent less to <br />9 percent more than Level II results. The poorest agreement is for far ranges, <br />beyond 150 km, where Level III values are from 7 to 28 percent high. Estimates of <br />SWE by the SAA are most suspect at far ranges at any rate because even the lowest <br />radar beam is well above the radar's elevation. <br /> <br />The degree of agreement in table 2 is considered quite reasonable. Even with Level <br />III data degraded from 0.5 to 5.0 dBZ resolution, SWE accumulations are within 12 <br />percent of Level II estimates to 150 km range and usually within 6 percent or less. <br />Radar-estimated storm total SWE accumulations can sometimes differ with surface <br /> <br />21 <br />