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

2. AATS-14 - like column and profiles Aerosol H 2 O O 3 AERONET-like Phase function Size mode distributions n re ( ), n im ( ) Single-scattering albedo Asymmetry parameter Shape Hence aerosol type Improve H 2 O, O 3 Add NO 2 Thus improve AOD Simultaneous spectra yield airborne profiles of aerosol type via Aeronet-like retrievals

3. 4STAR and its Use

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

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

6. Key Technological Hurdles 1.Maintaining calibration to 1% over a period of months 2.Stray light rejection: measure skylight within 3° of sun 3.Fiber optic couplings with <1% calibration stability (Connections/Rotation) 4.Sky scan within 100 seconds(10 km in flight)

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

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

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

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

11. Radiance Calibration 4STAR-Ground AERONET Cimel 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 flightNew collector design, 100X light volume. Goal: Sky-scan measurements within 100 seconds, 10 km in flight Mauna Loa, spectral Langley calibrationMauna Loa, spectral Langley calibration Add SWIR spectrometer for more size and absorption informationAdd SWIR spectrometer for more size and absorption information Continue spectral inversion developmentContinue spectral inversion development Harden design for airborne deploymentHarden design for airborne deployment Deploy in 2011: Western Atlantic Tropospheric Aerosol Campaign (WATAC)Deploy in 2011: Western Atlantic Tropospheric Aerosol Campaign (WATAC)