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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. Problem with Low Saturation

  6. SeaWiFS Solution Knee Values

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

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

  9. 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)?

  10. 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

  11. MODIS versus Others Band Center (Bandwidth) MODIS 665.1 (10) 676.7 (10) 746.4 (10) MERIS 665.0 (10) 681.3 (7.5) 709.0 (9) GLI 666.7 (10) 679.9 (10) 710.5 (10) GOCI 660.0 (20) 680.0 (10) 745.0 (20) NEL (mWcm-2m-1sr-1) MODIS 0.0008 0.0007 0.0009 MERIS 0.0013 0.0014 0.0011 GLI 0.0015 0.0014 0.0012 GOCI 0.0032 0.0031 0.0020 From Xing et al. (2007, Ocean Science Journal)

  12. MODIS/Aqua Lt (typical)

  13. MODIS/Aqua Lt (max)

  14. Lt Dynamic Range

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

  16. 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

  17. Surface PAR

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

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

  20. Sensitivity of Lw685 to solar/viewing geometry

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

  22. 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

  23. 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

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

  25. 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.

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

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

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

  29. 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

  30. 5/22/2004 Florida C. Harbor WFS What Time Is Desirable to Capture Diurnal Changes? Cyanobacteria (Trichodesmium erythraeum) blooms observed by GOES and MODIS

  31. 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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