MODIS/Aqua Atmospheric Correction Updates

A modification was made to the variation of Rayleigh scattering with atmospheric pressure, to account for the change with solar geometry. The refinement will be fully described in Wang, M., "A refinement for the Rayleigh radiance computation with variation of the atmospheric pressure," Int. J. Rem. Sens., in press. The effect of this change is negligible at low solar zenith angles, but large pressure deviations at higher solar angles can result in spectrally-dependent changes of order 5% in nLw.

In addition, the MODIS/Aqua Rayleigh tables and all band-averaged quantities (e.g., extraterrestrial solar irradiances) were update to use the best available knowledge of the relative spectral response (RSR) of the sensor bands. The current production tables were actually using Rayleigh tables based on MODIS/Terra RSRs. The spectral response function and source spectra are posted here. The Rayleigh tables were also extended to include additional windspeed dependence (more table entries), to be consistent with the tables used for all other sensors. After vicarious recalibration, the cumulative effect of these RSR-related changes was minor.

Last updated 19 January 2005, B. Franz