Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable 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 Destin, FL February , 2010

NASA Wind Lidar Science (WLS) Experiment at Howard Beltsville Research Facility GOALS Develop understanding of direct detection (GLOW) wind speed and direction performance for various cloud and aerosol loading conditions (pollution, cirrus), using the 355nm backscatter ratios and water vapor data independently measured by the Raman lidar as well as synergistic measurements from the Beltsville instrument suite. 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). Funded by NASA SED, ROSES07-WLS (Dr. Ramesh Kakar) A comparison of wind lidar technology is ongoing at the Howard University Beltsville Campus. The goal of the experiment was to compare two of NASA’s state-of-the-art wind lidar technology instruments. The VALIDAR is an aerosol-based lidar system from NASA/LaRC while the GLOW is a molecular-based lidar from NASA/GSFC. This experiment is the first time these two systems have been operated side by side. In addition, the commercial wind lidar from Leosphere, France (the WindCube), a 915 MHz profiler, ACARS winds and different types of radiosondes participated. 2

Goddard Lidar Observatory for Winds (GLOW) mobile Doppler lidar Overview for GLOW 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 15 km Elevation angle= 45 deg Scan pattern = 4 directions: (N,S,E,W)+vertical Dwell per LOS = 30 sec

GLOW at Beltsville Research Site

Upgrades for GLOW Laser ( 50Hz, 25mJ/pulse, Diode pumped ) Reference Signal Measurement Electronics ( Preamps, discriminators, boxcar integrators) Etalon Calibration

Laser Diode Pumped, 50Hz, 20mJ/pulse More Stable seed laser Less energy consumption improves the temperature stability inside GLOW

Reference Measurement Laser Reference Signal Sampling Optics Fiber Collimator Reference Signal Fiber From Telescope Lidar Signal Fiber M1 BS R=95%, T=5% To Receiver Lidar Signal+ Reference Signal IF

Etalon Calibration Scan

Wind Measurements in 2009 From Feb. 21 to Oct. 20, 50days, 310 hours Variety weather conditions: different aerosol loadings, cirrus clouds at different altitude, front passage. GLOW-Validar Intercomparison: Feb 21-Mar 10. GLOW/Validar/AT/ALVICE HURL/Sonde/915 MHz profiler Mar. 2009 Campaign: Mar. 20-31 . GLOW/AT/ALVICE HURL/Sonde/915 MHz profiler Regular GLOW/Sonde comparisons

Measurement Errors

Results from March 2009 Campaign

Weather Conditions ref0903201250.edg 0.742 Cloud ref0903240002.edg 2.0986 Thin Cloud 8-10km ref0903201918.edg 1.2136 Clear ref0903240249.edg 1.7475 ref0903202057.edg 3.35 ref0903242108.edg 2.5064 Thin Cloud 8 and 11km ref0903210037.edg 0.8791 ref0903250000.edg 3.7403 Increasing at 8,11km ref0903220247.edg 5.1409 ref0903250410.edg 2.7287 ref0903222005.edg 0.4775 mcs0903301411.edg 2.234722 ref0903222105.edg 0.3003 mcs0903301644.edg 0.561111 ref0903222146.edg 2.0066 mcs0903301721.edg 7.336667 ref0903230005.edg 3.4847 mcs0903310051.edg 1.013611 ref0903230439.edg 2.7164 mcs0903311302.edg 3.508333 Thin Clouds at 10 ref0903231856.edg 5.0214

Results from March 2009 Campaign

Results from March 2009 Campaign

Comparison with Radio Sondes

Comparison with Radio Sondes

Comparison with Radio Sondes

Comparison with Radio Sondes

Comparison with Radio Sondes

Comparison with Radio Sondes

Comparison with IAD Sondes

Summary and Future Work Wind measurement on regular basis Sonde comparison validation Continue wind data collection. 2 to 3 days a week Coordinate with NWAVES Use the GLOW data in WRF model Participate field campaigns

Comparison with Radio Sondes

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%

Sampling strategy: Post processing: 2 1 5 3 4 5 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 30 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) 1 2 3 4 5

Backups

1 2 3 4 5

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