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Some Practical Considerations for the GEO-CAPE Mission

Some Practical Considerations for the GEO-CAPE Mission Sensitivity, Saturation, Sun glint, Cloud cover, etc Chuanmin Hu, Zhongping Lee, Keping Du, Antonio Mannino. NASA GEO-CAPE Science Working Group Meeting 11-13 May 2011, Boulder, Colorado. Some practical considerations

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Some Practical Considerations for the GEO-CAPE Mission

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  1. Some Practical Considerations for the GEO-CAPE Mission Sensitivity, Saturation, Sun glint, Cloud cover, etc Chuanmin Hu, Zhongping Lee, Keping Du, Antonio Mannino NASA GEO-CAPE Science Working Group Meeting 11-13 May 2011, Boulder, Colorado

  2. Some practical considerations for the GEO-CAPE mission Sensitivity, Saturation, Sun glint, Cloud cover, etc Objectives Help define sensor constraints Help implement measurement plans NASA GEO-CAPE Science Working Group Meeting 11-13 May 2011, Boulder, Colorado

  3. Sensitivity versus Saturation SeaWiFS Florida Strait MODIS/Aqua Florida Strait

  4. MODIS FLH (ocean bands) MODIS RGB (land bands) Sensitivity versus Saturation

  5. MODIS versus SeaWiFS Units: mWcm-2m-1sr-1

  6. How Precise are MODIS Chl? 5-10% RMS speckle noise. Resolves to <0.005 mg m-3 at low concentrations

  7. MODIS Fluorescence Sensitivity Not sufficient to resolve Chl < 0.1 mg m-3 MODIS FLH MODIS/Aqua Chl, Sargasso Sea Then, how do we choose the trade between sensitivity and dynamic range (saturation)?

  8. MODIS versus SeaWiFS Radiance (L) units: mWcm-2m-1sr-1. Numbers in () are for SeaWiFS 1 DN of MODIS 678 band is corresponding to 0.1 – 0.2 mg m-3 Chl

  9. MODIS/Aqua Lt (typical)

  10. MODIS/Aqua Lt (max)

  11. Lt Dynamic Range

  12. Question With these MODIS-based settings, can GEO-CAPE differentiate fluorescence quantum efficience changes at large solar zenith angles?

  13. Morrison (2003, L&O) Decreased Photochemical Quenching Quantum Yield Increased Non-Photochemical Quenching 1 10 100 1000 PAR ( molem-2s-1) Chlorophyll fluorescence quantum yield 0= 70o 0= 60o 0= 80o

  14. Surface PAR

  15. Hours from Sunrise and Sunset PAR ~ 970 PAR ~ 600 PAR ~ 250

  16. Sensitivity of Lw685 to solar/viewing geometry

  17. Sensitivity of fluorescence (Lw685 and FLH) to solar/viewing geometry MODIS NEL (678 nm) ~ 0.001 mWcm-2m-1sr-1

  18. Morrison (2003, L&O) Decreased Photochemical Quenching Quantum Yield Increased Non-Photochemical Quenching 1 10 100 1000 PAR ( molem-2s-1) Chlorophyll fluorescence quantum yield 0= 70o 0= 60o 0= 80o

  19. Sensitivity of fluorescence (Lw685 and FLH) to solar/viewing geometry MODIS NEL (678 nm) ~ 0.001 mWcm-2m-1sr-1 Assuming MODIS sensitivity on GEO-CAPE and a constant fluorescence efficiency (quantum yield) of 2%, for Chl = 0.5, FLH decreased by 0.002 mWcm-2m-1sr-1 (nearly halved) from 0=60o to 70o. Quantum efficiency nearly doubled from 0=60o to 70o, resulting in similar FLH changes if everything else remains the same. Conclusion: With MODIS sensitivity on GEO-CAPE, it is possible to derive fluorescence quantum efficiency changes in the non-photochemical regime for Chl ~> 0.5 mg m-3

  20. June 22. # of hourly observations with non-photochemical quenching (100 < PAR < 1000) Dec. 22. # of hourly observations with non-photochemical quenching (100 < PAR < 1000)

  21. Summary on Sensitivity • MODIS sensitivity can serve as a good template Sufficient to resolve fluorescence quantum efficiency changes between 0=60o to 80o for Chl ~ 0.5 or higher • Saturation radiance determined from MODIS measurements (together with ACE missions). May need adjustment when global dataset is considered.

  22. Twice/day versus once/day Cloud Avoidance - TBD

  23. Sun Glint Considerations June 22. # of hourly observations with o< 80o June 22. # of hourly observations with sun glint (wind = 6 m/s)

  24. Sun Glint Considerations Dec. 22. # of hourly observations with o< 80o Dec. 22. # of hourly observations with sun glint (wind = 6 m/s)

  25. Sun Glint Is Not Always A Bad Thing Makes it easier to detect oil spills % of days showing surface oil presence, April 22 – July 31, 2010

  26. FLH Shows Greener NEGOM

  27. 5/22/2004 Florida C. Harbor WFS What Time Is Desirable to Capture Diurnal Changes? Cyanobacteria (Trichodesmium erythraeum) blooms observed by GOES and MODIS

  28. Conclusions - MODIS sensitivity can be followed - Saturation radiance may need adjustment - Need to implement a data acquisition matrix to optimize performance for science needs - Timing and frequency of measurements - Synoptic or targeted mode, where/when - Clouds and glint considerations NASA GEO-CAPE Science Working Group Meeting 11-13 May 2011, Boulder, Colorado

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