Huailin chen bruce gentry tulu bacha belay demoz demetrius venable destin fl february 2010
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Huailin Chen, Bruce Gentry, Tulu Bacha, Belay Demoz, Demetrius Venable Destin, FL PowerPoint PPT Presentation


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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.

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

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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)


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


Laser

Reference Signal Sampling Optics

M1

BS R=95%, T=5%

Lidar Signal+ Reference Signal

Fiber

Collimator

Fiber

Collimator

Reference Signal Fiber

To Receiver

IF

Lidar Signal Fiber

Fiber

Collimator

From Telescope

Reference Measurement


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


Results from March 2009 Campaign

March 22-23, 2009


Results from March 2009 Campaign

March 30-31, 2009


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

Wavelength354.7 nm

Telescope/Scanner Area0.116 m2

Laser Linewidth (FWHH)80 MHz

Laser Energy/Pulse 25 mJ @ 50pps

Etalon FSR 12 GHz

Etalon FWHH1.7 GHz

Edge Channel Separation5.1 GHz

Locking Channel Separation 1.7 GHz

Interference filter BW (FWHH)150 pm

PMT Quantum Efficiency22%


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  • 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)


Backups


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Combined Molecular Sensitivity vs. T and v

T= 150K to 350K , v = 0 to 100 m/s


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