1. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Short Course on Introduction to Meteorological Instrumentation and Observation Techniques WIND MEASUREMENTS Robert A. Baxter, CCM Parsons Engineering Science Pasadena, CA

2. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Session Overview Goal: Understand a general approach to measuring wind and setting up and calibrating the wind sensors

3. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Session Overview  References and guidance  Wind measurement  Wind speed  Wind direction Goal: Understand a general approach to measuring wind and setting up and calibrating the wind sensors

4. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements References and Guidance DocumentYear Quality Assurance Handbook for Air Pollution Measurement Systems Volume IV: Meteorological Measurements March, 1995 Meteorological Monitoring Guidance for Regulatory Modeling Applications February, 2000

5. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement of Wind  Wind is a vector quantity comprised of direction and speed

6. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement of Wind  Wind is a vector quantity comprised of direction and speed Measurement Method –vector quantity –Individual scalar quantities

7. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement of Wind  Wind is a vector quantity comprised of direction and speed Measurement Method –vector quantity –Individual scalar quantities Most common approach is to measure the individual scalar quantities

8. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Measurement Methods  Mechanical  Non-mechanical

9. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Measurement Methods  Mechanical –Cup and vane –Propeller/vane  Non-mechanical

10. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Measurement Methods  Mechanical –Cup and vane –Propeller/vane  Non-mechanical –Sonic –Hot wire

11. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Measurement Methods  Mechanical –Cup and vane –Propeller/vane  Non-mechanical –Sonic –Hot wire Focus on mechanical methods

12. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics  Siting and exposure

13. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics  Siting and exposure  Transfer function

14. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics  Siting and exposure  Transfer function  Starting threshold

15. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics  Siting and exposure  Transfer function  Starting threshold  Calibration and alignment methods

16. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics  Siting and exposure  Transfer function  Starting threshold  Calibration and alignment methods  Other characteristics –Distance constant –Damping ratio –Delay distance

17. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Siting For use in air quality modeling applications, meteorological data should be representative of conditions affecting the transport and dispersion of pollutants in the “area of interest” as determined by the locations of the sources and receptors being modeled

18. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Siting For use in air quality modeling applications, meteorological data should be representative of conditions affecting the transport and dispersion of pollutants in the “area of interest” as determined by the locations of the sources and receptors being modeled Representativeness –Simple Terrain –Complex Terrain –Coastal Locations –Urban Locations

19. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Simple Terrain

20. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Simple Terrain

21. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Urban Locations

22. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Urban Locations

23. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Urban Locations

24. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Siting and Exposure Urban Locations

25. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions

26. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions  Describes the relationship between the rate of rotation and the wind speed

27. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions  Describes the relationship between the rate of rotation and the wind speed  Determined through wind tunnel testing

28. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions  Describes the relationship between the rate of rotation and the wind speed  Determined through wind tunnel testing  Linear relationship above the starting threshold of the sensor

29. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions  Describes the relationship between the rate of rotation and the wind speed  Determined through wind tunnel testing  Linear relationship above the starting threshold of the sensor  Near threshold response –Cup anemometer –Propeller anemometer

30. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Wind Speed Transfer Functions What do the transfer functions look like?

32. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Starting Threshold The wind speed at which an anemometer or vane first starts to perform within its specifications

33. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Starting Threshold The wind speed at which an anemometer or vane first starts to perform within its specifications  Applies to both wind speed and wind direction

34. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Starting Threshold The wind speed at which an anemometer or vane first starts to perform within its specifications  Applies to both wind speed and wind direction  Wind tunnels are the only way to measure the starting threshold

35. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Starting Threshold The wind speed at which an anemometer or vane first starts to perform within its specifications  Applies to both wind speed and wind direction  Wind tunnels are the only way to measure the starting threshold  The starting threshold can be estimated by measuring the starting torque of the sensor

36. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Measurement Characteristics Starting Threshold Calculation T = K u 2 Where T is the torque( g-cm 2 /sec 2 ) u 2 is the square of the wind speed (m/s) K is the constant for the aerodynamic shape (g) u = (T/K)

37. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Calibration and Operation Wind Speed  Calibration in a wind tunnel

38. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Calibration and Operation Wind Speed  Calibration in a wind tunnel  Application of the transfer function –Cup anemometer –Propeller anemometer

39. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Calibration and Operation Wind Direction  Vane alignment  Sensor response and linearity

40. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Direction Vane Alignment  Finding true north –Magnetic north and declination correction –Solar methods and the “Baxter Method” –Alignment using GPS

41. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Using the Step-by-Step Solar Method for Alignment 1.Measure the relative pointing direction 2.Measure the sun’s relative azimuth angle 3.Calculate the sun’s actual azimuth angle 4.Calculate the local deviation 5.Calculate the cross are true alignment 6.Align the wind direction sensor

42. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements GPS Method for Alignment  Walk off the alignment direction

43. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Wind Direction Vane Linearity  Rotation through full range  Alternative methods to protractor  Reverse rotation

44. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Review of Wind Measurement  References and guidance  Siting and exposure  Measurement characteristics –Starting threshold –Transfer function  Calibration methods

46. Short Course on Introduction to Meteorological Instrumentation and Observations Techniques Wind Measurements Sun Angle Back