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What happens during wavelength recalibration in FLAASH?

During wavelength recalibration in FLAASH, how are the wavlength shifts performed and do the FWHM (full width at half-maximum) change as well?

The shift is determined and added to the nominal wavelengths, then on the second call to FLAASH, the new calibration is used in place of the nominal one. The calibration enters the calculation in that the MODTRAN runs are sampled via the channel profiles. Each channel profile is centered on its calibrated wavelength, and the MODTRAN sampling degrades the high resolution of the MODTRAN run to that of the hyperspectral instrument.

There is no resampling of the input radiance data; rather, the recalibration changes the wavelength values to which the radiances are assigned. The new wavelength values are used in the MODTRAN simulations to generate the atmospheric correction. The FWHMs remain the same.

Review on 12/31/2013 MM


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