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Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable Wintergreen, VA

Goddard Lidar Observatory for Winds (GLOW) Wind Profiling from the Howard University Beltsville Research Facility. Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable Wintergreen, VA June, 2009.

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Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable Wintergreen, VA

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  1. Goddard Lidar Observatory for Winds (GLOW) Wind Profiling from the Howard University Beltsville Research Facility Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable Wintergreen, VA June, 2009

  2. NASA Wind Lidar Science (WLS) Experiment at Howard Beltsville Research Facility GOALS • Develop understanding of direct detection (GLOW) and coherent Doppler lidar (VALIDAR) wind performance for various cloud and aerosol loading conditions (pollution, cirrus) • Develop a seasonal data base archive for wind measurements. • Intercomparison of coherent and direct detection Doppler lidars • Compare Doppler lidar wind data to other sensors (Profiler, Radiosonde, ACARS). • Hands-on student training • Funded by NASA SED, ROSES07-WLS (Dr. Ramesh Kakar)

  3. GLOW -February 24, 2009 RS92 Sonde 1 RS92 Sonde 1 RS92 Sonde 2 RS92 Sonde 2 m/s deg Direct Detection Doppler lidar profiling at Howard Beltsville Research Facility • Goddard Lidar Observatory for Winds (GLOW) mobile Doppler lidar • Direct detection Doppler Lidar system • Measures clear air wind profiles using molecular backscatter • Serves as technology testbed for air and space based lidar technologies • Multiple field campaigns since 2000 915 MHz wind profiler and local radiosonde launches provide correlative measurements for the wind lidar systems • Measurement summary • Vertical resolution=250 m • t=3 min • Altitude range= 2 to 5 km • Elevation angle= 45 deg • Scan pattern = 4 directions: (N,S,E,W)+vertical • Dwell per LOS = 30 sec GLOW mobile Doppler lidar

  4. 2 1 3 5 4 2 1 5 3 4 • Sampling strategy: • LOS scans at multiple azimuths • in repeating cycle (5-10 LOS /cycle) • Step stare scan pattern at fixed elevation angle (Typ. 45 deg) : 4 cardinal directions (N,S,E,W) + vertical • Signals are range gated in 45 m bins, • integrated and stored every 10 s. Three • dwells (30s total) per LOS. Total time to complete scan: ~3 min • Post processing: • data averaged in range (default 250 m) • data can be accumulated in time by LOS • (multiples of base 3 min) • corrections for atmos. T and P (RBS)

  5. GLOW Lidar System Parameters Wavelength 354.7 nm Telescope/Scanner Area 0.116 m2 Laser Linewidth (FWHH) 80 MHz Laser Energy/Pulse 25 mJ @ 50pps Etalon FSR 12 GHz Etalon FWHH 1.7 GHz Edge Channel Separation 5.1 GHz Locking Channel Separation 1.7 GHz Interference filter BW (FWHH) 150 pm PMT Quantum Efficiency 22%

  6. GLOW Signal Dynamic Range

  7. February 24, 2009 z=250 m ; t=3 min ~45 min RS92 sonde RS92 sonde Clouds 2 km Signals exceed max count rate below 2 km. PMTs gated off

  8. February 24, 2009 GLOW profile: 0126 UT Sonde launched: 0059 UT GLOW 3 min average; Sonde averaged to z=250 m

  9. Exploring Differences in Spatial and Temporal Sampling- GLOW vs Sonde = sonde altitude at time of lidar measurement. Assumes rise rate of 5 m/s.

  10. February 24, 2009 GLOW profile: 0150 UT Sonde launched: 0128 UT GLOW 30 min running average; Sonde averaged to z=250 m

  11. February 24, 2009

  12. February 24, 2009 GLOW profile: 0417 UT Sonde launched: 0329 UT GLOW 33 min running average; Sonde averaged to z=250 m

  13. GLOW-Sonde February 24, 2009 GLOW profile: 0357 UT Sonde launched: 0329 UT GLOW 33 min running average; Sonde averaged to z=250 m

  14. March 18, 2009 z=250 m ; t=3 min

  15. April 9, 2009 z=250 m ; t=3 min

  16. March 11, 2009 z=250 m ; t=3 min ; 9 min running average

  17. March 11, 2009 z=100 m ; t=3 min; 3 min average

  18. Edge Technique Lab Testbed Edge Technique Lidar System (1995) • Objectives • Demonstrate atmospheric wind measurement capabilities • Prove new concepts and test components • Validate space simulation instrument model PBL Lidar Winds1 10 sec (100 shot) averaging/LOS; 22 m vertical resolution Transmitter Wavelength (nm) : 1064 Repetition rate (Hz) : 10 Energy per pulse (J) : 0.12 Laser bandwidth (MHz) : 40 Receiver Telescope diameter (m) : 0.406 Interference filter bandwidth (nm) : 5 Quantum efficiency : 0.40(analog) 0.04(PC) Fabry-Perot interferometer Spectral width FWHM (MHz) : 100 Free Spectral Range (GHz) : 3 1. Korb, C. L, B. Gentry, and S. X. Li, (1997) “Edge Technique Doppler Lidar Wind Measurements with High Vertical Resolution,” Applied Optics, 36, pp. 5976-5983

  19. Future Work • Continue wind profile data collection. • 2 to 3 days a week • Coordinate with NWAVES • Examine representativeness of data sampling and averaging schemes • Continue inter-comparisons with other wind sensors (VALIDAR, ACARS, sondes, profiler • Examine effects of clouds and aerosols on the molecular wind measurement using Raman lidar backscatter products as a reference • Resurrect the double edge aerosol receiver for PBL studies

  20. Backups

  21. Direct Detection Doppler lidar profiling at Howard Beltsville Research Facility • Goddard Lidar Observatory for Winds (GLOW) mobile Doppler lidar • Direct detection Doppler Lidar system • Measures clear air wind profiles using molecular backscatter • Serves as testbed for air and space based lidar technologies • Multiple field campaigns since 2000 Line of sight wind profiles are sequentially measured at 4 azimuth angles (N,S,E,W)+vertical. The multiple direction LOS profiles are combined to produce vertical profiles of horizontal wind speed and direction (right) • Measurement summary • Vertical resolution=250 m • t=3 min • Altitude range= 2 to 5 km • Elevation angle= 45 deg • Scan pattern = 4 directions: (N,S,E,W)+vertical • Dwell per LOS = 30 sec

  22. February 24, 2009 GLOW profile: 0417 UT Sonde launched: 0329 UT GLOW 33 min running average; Sonde averaged to z=250 m

  23. GLOW-Sonde February 24, 2009 GLOW profile: 0417 UT Sonde launched: 0329 UT GLOW 33 min running average; Sonde averaged to z=250 m

  24. February 24, 2009 GLOW profile: 0126 UT Sonde launched: 0059 UT GLOW 33 min running average; Sonde averaged to z=250 m

  25. March 11, 2009 33 min

  26. March 11, 2009 9 min

  27. March 11, 2009 3 min 100 m

  28. 2 1 5 3 4

  29. Combined Molecular Sensitivity vs. T and v T= 150K to 350K , v = 0 to 100 m/s

  30. March 31, 2009 GLOW profile: 0150 UT Sonde launched: 0128 UT Sonde averaged to z=250 m

  31. March 23, 2009 z=250 m ; t=3 min

  32. February 24, 2009

  33. February 24, 2009

  34. March 30, 2009 z=250 m ; t=3 min

  35. March 31, 2009 GLOW profile: 0140 UT Sonde launched: 0128 UT GLOW 30 min running average; Sonde averaged to z=250 m

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