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CNS Meteorological System Upgraded 100-meter tower in 2004 to include a dual elevator on the same tower face Dual monitoring systems with independence from sensor to Plant Computer Wind Sensors have Cups/Vanes on one side and Sonic on the other

Meteorological Parameters Systems A and B 10, 60, and 100 meter wind speed and direction 3 Delta-ts (60m-10m, 100m-10m, 100m-60m) 10, 60, and 100 meter temperatures System A only 10 meter dew point Station Pressure Precipitation

Meteorological Equipment System A Climatronics F460 Wind speed and Direction Sensors Climatronics Temperature Sensors Tower Systems Elevator Climatronics Dew Point Sensor Climatronics Tipping Bucket Rain gauge with Wind Shield Campbell Scientific 23X Micro Dataloggers Climatronics Pressure Sensor

Meteorological Equipment System B Met One 50.5 Sonic Wind speed and Direction Sensors Climatronics Temperature Sensors Tower Systems Elevator Campbell Scientific 23X Micro Dataloggers

Purpose Independently verify wind data collected from both systems are not statistically different Data from System A (cup/vane) can be interchanged with data from System B (sonic) Demonstrate the impact of the tower structure on meteorological data

Data Set One year of onsite validated hourly meteorological data (October 31, 2004 October 30, 2005) 8784 possible hourly values for each parameter for both Systems A and B on the 100-meter tower

Methodology Remove bad data from System A and System B files including calibrations, frozen sensors, failed sensors, bad data spikes, etc Remove wind directions when wind speeds less than 3 mph and/or wind directions are through tower Remove wind speeds when wind directions are through tower

Table 3 1 Invalid Data for CNS Onsite Meteorological Program October 31, 2004 October 30, 2005 Parameter Missing/Bad Data Hours Problem All Parameters (A&B) 3/29 1400 4/1 1200 4/4 0800 4/5 1500 103 Spring Calibration All Parameters (A System Only) 8/3 0800 8/4 0800 25 Troubleshoot All 3 levels down All Parameters (A&B) 9/26 0900 09/29 1700 81 Fall Calibration 100 Meter Wind Speed (A) 1/3 0700 1/9 1300 2/6 2300 2/9 2100 (B) 1/12 0800 1600 221 9 Frozen Sensor Bad Data-Spike 60 Meter Wind Speed (A)1/3 0700 1/9/ 1300 4/2 0600 8/13 1600 9/28 1900 10/31 2400 (B) 1/21 1900 2100 4153 3 Frozen Sensor/Sensor Failure Bad Data-Spike 10 Meter Wind Speed (A)1/3 0700 1/9 1300 151 Frozen Sensor 100 Meter Wind Direction (B) 1/12 0800 1600 9 Bad Data-Spike 60 Meter Wind Direction (B) 1/21 1900 2100 3 Bad Data-Spike

Wind Directions from 195-245 degrees blow through tower Window is 25 degrees for vane and cup sensors and 30 degrees for sonic sensor

Data Availability 100- meter wind speed 82% 60-meter wind speed 87% 10-meter wind speed 88% 100-meter wind direction 84% 60-meter wind direction 45% 10-meter wind direction 70%

Results Unobstructed with no tower influence

Wind Speed Averages Hours A Avg. B Avg. Diff. Abs. 100-M 7433 13.9 12.8 1.4 1.4 WS 60-M 7637 11.8 10.3 1.5 1.6 WS 10-M 7754 7.8 7.0 0.9 0.9 WS

Wind Speed Correlation Hours Diff. Slope Y-int. Corr. 100-M 7433 1.4 1.02 0.95 0.98 WS 60-M 7637 1.5 1.06 0.84 0.99 WS 10-M 7754 0.9 1.01 0.62 0.99 WS

Figure 1: 100-Meter Wind Speed Regression 50.0 45.0 40.0 y = 1.0159x + 0.9484 Observations: 7183 Correlation: 0.98 100-Meter A (Cup) Wind Speed 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 100-Meter B (Sonic) Wind Speed

Figure 2: 60-Meter Wind Speed Regression 45.0 40.0 35.0 y = 1.0621x + 0.8437 Observations: 7637 Correlation: 0.99 60-Meter A (Cup) Wind Speed 30.0 25.0 20.0 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 60-Meter B (Sonic) Wind Speed

Figure 3: 10-Meter Wind Speed Regression 40.0 35.0 y = 1.0141x + 0.6284 Observations: 7754 30.0 Correlation: 0.99 10-Meter A (Cup) Wind Speed 25.0 20.0 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 10-Meter B (Sonic) Wind Speed

Wind Direction Averages Hours A Avg. B Avg. Diff. Abs. 100-M 7375 184 182 2.6 3.0 WD 60-M 3970 184 180 3.6 4.0 WD 10-M 6148 195 189 6.7 7.0 WD

Wind Direction Correlation Hours Diff. Slope Y-int. Corr. 100-M 7375 2.6 1.02 0.87 0.99 WD 60-M 3970 3.6 1.03 1.30 0.99 WD 10-M 6148 6.7 1.02 3.08 0.99 WD

Figure 4: 100-Meter Wind Direction Regression 400 350 300 y = 1.0191x - 0.8727 Observations: 7375 Correlation: 0.99 100-Meter A (Vane) Wind Direction 250 200 150 100 Tower interference 50 0 0 50 100 150 200 250 300 350 400-50 100-Meter B (Sonic) Wind Direction

Figure 5: 60-Meter Wind Direction Regression 400 350 300 y = 1.0271x - 1.2974 Observations: 3970 Correlation: 0.99 60-Meter A (Vane) Wind Direction 250 200 150 100 Tower interference 50 0 0 50 100 150 200 250 300 350 400-50 60-Meter B (Sonic) Wind Direction

Figure 6: 10-Meter Wind Direction Regression 400 350 300 y = 1.0191x + 3.0831 Observations: 6148 Correlation: 0.99 10-Meter A (Vane) Wind Direction 250 200 150 100 Tower interference 50 0 0 50 100 150 200 250 300 350 400 10-Meter B (Sonic) Wind Direction

Tower Impacts Wind Speed and Direction

Wind Directions from 195-245 degrees blow through tower Window is 25 degrees for vane and cup sensors and 30 degrees for sonic sensor

100-m Wind Speed Averages Tower Impact Hours A Avg. B Avg. Diff. Abs. 100-M 409 10.0 12.7-2.7 3.0 WS-A 100-M 266 13.4 7.3 6.1 6.1 WS-B

100-m Wind Speed Correlation Tower Impact Hours Diff. Slope Y-int. Corr. 100-M 409-2.7 0.64 1.86 0.92 WS-A 100-M 266 6.1 1.68 1.11 0.89 WS-B

Figure 10: 100-meter Wind Speed Regression When Tower Impacts System A (Cups) 30.0 25.0 y = 0.6409x + 1.8626 Observations: 409 Correlation: 0.92 100-Meter A (Cup) Wind Speed 20.0 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 100-Meter B (Sonic) Wind Speed

Figure 11: 100-Meter Wind Speed Regression When Tower Impacts System B (Sonic) 45.0 100-Meter System A (Cup) Wind Speed 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 y = 1.681x + 1.1097 Observations: 268 Correlation: 0.89 0.0 0.0 5.0 10.0 15.0 20.0 25.0 100-Meter B (Sonic) Wind Speed

60-m Wind Speed Averages Tower Impact Hours A Avg. B Avg. Diff. Abs. 60-M 364 9.8 10.3-0.5 1.5 WS-A 60-M 285 10.5 6.6 3.9 3.9 WS-B

60-m Wind Speed Correlation Tower Impact Hours Diff. Slope Y-int. Corr. 60-M 364-0.5 0.79 1.68 0.94 WS-A 60-M 285 3.9 1.60-0.02 0.97 WS-B

Figure 12: 60-Meter Wind Speed Regression When Tower Impacts System A (Cups) 30.0 25.0 y = 0.7889x + 1.6774 Observations: 364 Correlation: 0.94 60-Meter A (Cup) Wind Speed 20.0 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 60-Meter B (Sonic) Wind Speed

Figure 13: 60-Meter Wind Speed Regression When Tower Impacts System B (Sonic) 35.0 60-Meter B (Sonic) Wind Speed 30.0 25.0 20.0 15.0 10.0 y = 1.6029x - 0.024 Observations: 285 Correlation: 0.97 5.0 0.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 60-MeterA (Cup) Wind Speed

10-m Wind Speed Averages Tower Impact Hours A Avg. B Avg. Diff. Abs. 10-M 394 7.7 8.1-0.4 1.2 WS-A 10-M 225 7.1 4.3 2.8 2.8 WS-B

10-m Wind Speed Correlation Tower Impact Hours Diff. Slope Y-int. Corr. 10-M 394-0.4 0.80 1.19 0.97 WS-A 10-M 225 2.8 1.68-0.12 0.95 WS-B

Figure 14: 10-Meter Wind Speed Regression When Tower Impacts System A (Cups) 25.0 y = 0.801x + 1.1866 20.0 Observations: 394 Correlation: 0.97 10-Meter A (Cup) Wind Speed 15.0 10.0 5.0 0.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 10-Meter B (Sonic) Wind Speed

Figure 15: 10-Meter Wind Speed Regression When Tower Impacts System B (Sonic) 30.0 10-Meter A (Cup) Wind Speed 25.0 20.0 15.0 10.0 y = 1.6833x - 0.1175 Observations: 225 Correlation: 0.95 5.0 0.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 10-Meter B (Sonic) Wind Speed

100-m Wind Direction Averages Tower Impact Hours A Avg. B Avg. Diff. Abs. 100-M 451 203 199 4 4 WD-A 100-M 145 240 235 5 5 WD-B

100-m Wind Direction Correlation Tower Impact Hours Diff. Slope Y-int. Corr. 100-M 451 4 0.96 12.9 0.97 WD-A 100-M 145 5 0.90 28.9 0.94 WD-B

Figure 16: 100-Meter Wind Direction Regression When Tower Impacts System A (Vane) 220 215 y = 0.9561x + 12.894 Observations: 451 100-Meter A (Vane) Wind Direction 210 205 200 Correlation: 0.97 195 190 185 190 195 200 205 210 215 100-Meter B (Sonic) Wind Direction

Figure 17: 100-Meter Wind Direction Regression When Tower Impacts System B (Sonic) 250 248 y = 0.8958x + 28.931 246 Observations: 145 100-Meter A (Vane) Wind Direction 244 242 240 238 236 Correlation: 0.94 234 232 230 228 230 232 234 236 238 240 242 244 100-Meter B (Sonic) Wind Direction

10-m Wind Direction Averages Tower Impact Hours A Avg. B Avg. Diff. Abs. 10-M 402 203 197 6 6 WD-A 10-M 80 243 236 7 7 WD-B

10-m Wind Direction Correlation Tower Impact Hours Diff. Slope Y-int. Corr. 10-M 402 6 0.98 11.2 0.99 WD-A 10-M 80 7 1.01 4.0 0.95 WD-B

Figure 18: 10-Meter Wind Direction Regression When Tower Impacts System A (Vane) 215 10-Meter A (Vane) Wind Direction 210 205 200 195 y = 0.9757x + 11.2 Observations: 402 Correlation: 0.99 190 180 185 190 195 200 205 210 10-Meter B (Sonic) Wind Direction

Figure 19: 10-Meter Wind Direction Regression When Tower Impacts System B (Sonic) 252 10-Meter A (Vane) Wind Direction 250 248 246 244 242 240 238 236 y = 1.0125x + 3.9992 Observations: 80 Correlation: 0.95 234 232 228 230 232 234 236 238 240 242 244 10-Meter B (Sonic) Wind Direction

Conclusions Outside of Tower wake impacts, Systems A and B are statistically the same for WS/WD. Outside of Tower wake impacts, all differences are small. WD small bias likely due to alignment errors during calibration.

Conclusions (cont d) Cup anemometer records wind speed on average 1mph higher than sonic likely due to overspeeding. Tower wake has greatest impact on wind speed. Differences up to 10 mph seen at wind speeds above 25 mph. Appears the wind speed tower impact is largest on sonic sensors but is it? Data from either system are interchangeable

Conclusions (cont d) Tower wake has little to no impact on wind direction on either vane or sonic sensors. Data from either System A (cups/vanes) or System B (sonic) are interchangeable outside of tower wake. Within wake, data scrutiny is needed either manually or with software.