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Detector dependency of MODIS Polarization Sensitivity derived from on-orbit characterization

Detector dependency of MODIS Polarization Sensitivity derived from on-orbit characterization. Gerhard Meister a,b , Bryan A. Franz b,c , Ewa J. Kwiatkoska d , Robert E. Eplee e,b , Charles R. McClain b,c a: Futuretech Corp. b: OBPG (Ocean Biology Processing Group)

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Detector dependency of MODIS Polarization Sensitivity derived from on-orbit characterization

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  1. Detector dependency of MODIS Polarization Sensitivity derived from on-orbit characterization Gerhard Meistera,b, Bryan A. Franzb,c, Ewa J. Kwiatkoskad, Robert E. Epleee,b, Charles R. McClainb,c a: Futuretech Corp. b: OBPG (Ocean Biology Processing Group) c: NASA Goddard Space Flight Center, Code 614.2 d: TEC-EEP, ESTEC, ESA e: SAIC 8/03/09 Earth Observing Systems XIV, SPIE Optics and Photonics 2009, San Diego

  2. Optimization process Lm: MODIS measured TOA radiance (without polarization corr.) LTOA: modeled (nLw from SeaWiFS, aerosols from MODIS NIR bands) Q, U: Stokes vector parameters (modeled from Rayleigh) Lm = M11LTOA + M12Q + M13U • find best M11, M12, M13 per band, detector, and mirror-side • M11, M12, M13 = f (scan angle), cubic (M11) and linear (M12) • do this for one day per month over the mission lifespan • optimize over global distribution of path geometries

  3. M12: MODIS Terrablue band temporal trends Mirror side 1 Mirror side 2 M12 acts on the Q component 412 Detector 4 443 Space View (lunar) frame Nadir frame Solar Diffuser frame 488

  4. Blue band RVS & polarization sensitivity MS1, Detector 4 M13 fixed to pre-launch 412 443 488

  5. More microwave sensitivities: to rain

  6. Aerosol sensitivity to surface albedo A “critical surface albedo” exists for which sensitivity to aerosol completely disappears! ϖ0 Seidel & Popp, AMT, 2012

  7. Aerosol sensitivity to surface albedo A “critical surface albedo” exists for which sensitivity to aerosol completely disappears! AOD retrieval error at 550 nm. Plus (minus) signs denote an overestimate of surface albedo by 0.01 (-0.01). Seidel & Popp, AMT, 2012

  8. Sensitivity studies: useful for lots of things • Impact of instrument errors on retrievals • Best channels to retrieve certain variables • Qualitative picture of retrieval errors vs. different quantities (e.g. aerosol vs. surface albedo) • Impact of uncertainties in other variables on retrievals: e.g. cloud temperatures on cloud water path from Vis/NIR.

  9. 2D Gaussian

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