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A collaboration involving:

4S TAR : S pectrometer for S ky- S canning, S un- T racking A tmospheric R esearch. A collaboration involving:. NASA Ames: P. Russell, J. Redemann, S. Dunagan, R. Johnson, J. Zavaleta PNNL: B. Schmid, C. Flynn, E. Kassianov NASA GSFC: AERONET Team.

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A collaboration involving:

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  1. 4STAR:Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research A collaboration involving: NASA Ames: P. Russell, J. Redemann, S. Dunagan, R. Johnson, J. ZavaletaPNNL: B. Schmid, C. Flynn, E. KassianovNASA GSFC: AERONET Team

  2. 4STAR:Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research AERONET-like • Phase function • Size mode distributions • nre(l), nim(l) • Single-scattering albedo • Asymmetry parameter • Shape • Hence aerosol type • AATS-14 - like • column and profiles • Aerosol • H2O • O3 Improve H2O, O3 Add NO2 Thus improve AOD Simultaneous spectra yield airborne profiles of aerosol type via Aeronet-like retrievals

  3. 4STAR and its Use

  4. AATS-14 • NASA Ames • Airborne Tracking • Sunphotometers • Since 1996 • 13 Field Campaigns • >70 Publications AATS-6

  5. Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) Fiber Optics Cable Optical Entrance Sun Tracking Head Motor Feedback Devices Optical Entrance Elevation Motor Aircraft Skin Azimuth Motor Slip Ring Fiber Optics Rotating Joint

  6. Key Technological Hurdles • Maintaining calibration to 1% over a period of months • Stray light rejection: measure skylight within 3° of sun • Fiber optic couplings with <1% calibration stability (Connections/Rotation) • Sky scan within 100 seconds(10 km in flight)

  7. Ground Prototype (4STAR-Ground) Zeiss MCS CCD spectrometer Quasi-monolithic, no moving parts, ceramic body, Range: 250-1016 nm, Resolution ~ 2 nm `

  8. Direct Beam Comparison AATS-14 4STAR-Ground

  9. Direct Beam ComparisonAATS-14 & 4STAR-Ground Transmittance UT

  10. 4STAR-Ground AERONET Cimel Jens Redemann Roy Johnson

  11. Radiance Calibration AERONET Cimel 4STAR-Ground NASA Ames 30” Sphere

  12. 4STAR and AERONET principal plane scan

  13. Straylight rejection close to Sun

  14. Size Distribution Retrieval using AERONET Code

  15. Rotating Fiber Optics Coupling Throughput Repeatability

  16. Next steps… • New collector design, 100X light volume. Goal: Sky-scan measurements within 100 seconds, 10 km in flight • Mauna Loa, spectral Langley calibration • Add SWIR spectrometer for more size and absorption information • Continue spectral inversion development • Harden design for airborne deployment • Deploy in 2011: Western Atlantic Tropospheric Aerosol Campaign (WATAC)

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