MODIS/Aqua Normalization for Reflection/Refraction Effects

Note that the application of both corrections is conceptually equivalent to the Gothic-R term described in Morel et al. 2002. The proposed correction is minimal at low solar zenith angles. It becomes significant above 50 degrees, reaching ~5% at 60 degrees and 10-20% at 75 degrees solar zenith (highest at longest wavelengths). The correction also accounts for changes in sea surface conditions, as the downwelling reflection/refraction losses diminish with increasing wind speed (surface roughness).

References

Franz, B.A., R.E. Eplee, Jr., S.W. Bailey, and M. Wang, 2000: Changes to the atmospheric correction algorithm and retrieval of oceanic optical properties. In: Patt, F.S. and 17 co-authors, 2000: Algorithm updates for the fourth SeaWiFS data reprocessing. Hooker, S.B. and E.R. Firestone, Eds. NASA/TM-2003-206892, Vol. 22, NASA Goddard Space Flight Center, Greenbelt, Maryland, 29-33.

Mobley, C.D.,1994: Light and Water. Academic Press, Inc., San Diego, California, 592 pp.

Morel A., D. Antoine, B. Gentilli, 2002: Bidirectional reflectance of oceanic waters: accounting for Raman emission and varying particle scattering phase function. Appl. Opt., 41(30), 6289-6306.

18 January 2005, P. Jeremy Werdell, NASA Ocean Biology Processing Group, SSAI