1. VI-5474(NotesModisViirsStm10) 1 Using Sun and Aureole Measurements to Check MODIS COD and R eff Retrievals for Cirrus Prepared for MODIS/VIIRS Science Team Meeting J.G. DeVore, A.T. Stair, A.J. LePage, D. Villanucci, … Washington, DC January 2010 Please open in “Notes” mode to see the notes.

2. VI-5474(NotesModisViirsStm10) 2 1. Introduction Cirrus is important for climate - ~ 25% coverage globally Climate effects are poorly understood - In-situ measurement is difficult - Reason for SPARTICUS, MACPEX Remote measurement is difficult - Complex shapes - Strong forward scattering Sun and aureole measurements, SAM 1 (see notes in section 10) - New validation tool 2 - Data will be available during above campaigns

3. VI-5474(NotesModisViirsStm10) 3 2. SAM Calibration SAM radiance measurements - Solar disk and aureole profiles  At 670 +/- 5 nm - Lab calibration NIST traceable - Field OD secondary calibration using AERONET - Integration time and temperature corrected - Radiometric radiance accuracy:  Aureole ~15%  Disk <1% if OD<~0.6, <~10% otherwise - Aureole profile gradient (precision) <0.5%

4. VI-5474(NotesModisViirsStm10) 4 3. Example 1: GSFC 11 NOV 08 MODIS retrievals of COD and R eff are nearly uniform LOS parallax is accounted for

5. VI-5474(NotesModisViirsStm10) 5 4. SAM Disk, Aureole Profiles SAM aureole profiles are nearly identical Black curve shows center and inter-measurement spread

6. VI-5474(NotesModisViirsStm10) 6 5. Data And MCAP Simulations 3 Simulations using MODIS COD, R eff, and Yang/Baum phase functions don’t match data

7. VI-5474(NotesModisViirsStm10) 7 6. Example 2: GSFC 10 FEB 09 Simulations using MODIS COD, R eff, and Yang/Baum phase functions don’t match data

8. VI-5474(NotesModisViirsStm10) 8 7. Example 3: GSFC 10 FEB 09 When COD is adjusted ad hoc, the simulated aureole is too high

9. VI-5474(NotesModisViirsStm10) 9 8. COD Corrections Attempted 4 Delta photons for MODIS Forward scattering for SAM

10. VI-5474(NotesModisViirsStm10) 10 9. Conclusions SAM is a new Cal/Val technique - Suggest independent verification - Review MODIS phase functions Perform comparisons with other datasets - Raman lidar, MFRSR, GOES, CALIPSO, SPARTICUS Develop SAM OD correction for forward scattering - Use aureole measurements - Verify and validate

11. VI-5474(NotesModisViirsStm10) 11 10. Acknowledgements and End Notes 1 SAM is described in a recent paper: J. Atmos. Ocen. Tech., 25, pgs 2531-2548, 2009 The authors acknowledge and thank: Dr. Hal Maring and the NASA Science Mission Directorate for support through a ROSES grant, 2 Dr. Bryan Baum and Prof. Ping Yang, who suggested this line of research, 3 Dr. Yu You (TAMU), who has performed scattering calculations, showing similar effects on SAM COD measurements, and 4 Drs. Steve Platnick and Zhibo Zhang (GSFC), for their help with the MODIS delta photon correction.

12. VI-5474(NotesModisViirsStm10) 12 Deployed SAM Instruments SAM #303 at NASA/GSFC SAM #300 at DOE/ARM CF (OK)

13. VI-5474(NotesModisViirsStm10) 13 SAM Applications Climate (cloud) monitoring Cloud physics research Satellite algorithm cal/val Circumsolar radiation Dr. John DeVore 781-791-3209 devore@visidyne.com Dr. A.T. Stair 781-273-2820 ats@visidyne.com Contacts: