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Meeting of the Working Group on Space-Based Lidar Winds

Sedona, ArizonaFebruary 2004

GroundWinds New Hampshire and Hawaii Updates

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GroundWinds NH

• Direct-detection Doppler lidar– Operates at 532 nm – 3.5 W @ 10 Hz– 0.5 meter aperture– High-resolution

molecular and aerosol channels

– CCD detectors– 0.7-18 km range ASL

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GroundWinds NH Operations

• Operates weekly (weather permitting)• ~80 days of measurements since June 2003• Operating staff reduced for efficiency and an

increased focus on BalloonWinds• Utilized as test bed for GroundWinds Hawaii

and BalloonWinds • Participated in an inter-comparison campaign

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October 2003 CampaignObjective

• Inter-comparison campaign with Mini-MOPA: October 24th-31st

• Over 40 hours of coincident data• Objective of the campaign was to

address instrument– precision– accuracy– sensitivity

• Data in early stages of analysis

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October 2003 CampaignPrecision Investigation

• Instrument variations– Principle component analysis

• Atmospheric variations– Velocity spectra– Time series cross-correlation

• Statistical variations– Cramer-Rao lower bound with instrument

characteristics and line shape• Total variation

– RSS of instrument, atmospheric, and statistical variations

– Variance of LOSH velocity time series

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October 2003 CampaignAccuracy Investigation

• Accuracy to be characterized by an inter-comparison with coincident LOSH measurements made by Mini-MOPA

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October 2003 CampaignSensitivity Investigation

• Instrument sensitivity to be addressed by– Out-going laser power– Atmospheric optical properties– Instrument optical throughput– Photo-electrons detected– Detector characteristics– Precision of measurement

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GroundWinds HI

• Direct-detection Doppler lidar– Operates at 355 nm – 3.5 W @ 10 Hz– 0.5 meter aperture– High-resolution

molecular and aerosol channels

– CCD detectors– 4.0-21 km range ASL

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GroundWinds HI Operations

• Operates daily (weather permitting)

• ~86 days of measurements since June 2003

• Aerosol channel has been temporarily removed for BalloonWinds activities

• Performed facility maintenance after 8 months of operations

• Planning an instrument validation

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GroundWinds Measurement

Spectral measurement deconvolved and separated into Mie, Rayleigh, and Brillouin components

Frequency [1/cm]

Inte

nsity

[a.

u.]

Brillouin

Rayleigh

Mie

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Scattering Models

• The aerosol scattering model, which includes the Mie component, is approximated by the unbroadened laser measurement

• The molecular scattering model, which includes the Rayleigh and Brillouin components, is approximated by the Tenti model. An improved model is currently being developed at UNH.

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GWNH Aerosol Scattering RatioASR=A/(A+M)

1976 StandardAtmosphere

300 K1.0 Atm

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GWHI Aerosol Scattering RatioASR=A/(A+M)

1976 StandardAtmosphere

300 K1.0 Atm

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Scientific Studies• Molecular scattering model

– Understanding of molecular return signal– Additional data products

• Aerosol optical properties – Air quality studies– Extinction:backscatter ratio @ 355 & 532 nm

• Turbulence– Work not specific to lidars– TurbFest campaign paper submitted

• …

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GroundWinds Contact

• We welcome opportunities to collaborate with other organizations.

• Please contact us if you are interested in current or potential GroundWinds studies: ivan.dors@unh.edu