Influence of lower stratospheric aerosol variations on guidestar performance.
The probability distribution function for the logarithm of the mixing scatter ratio, based on long-term measurements of lower-stratospheric aerosol loading, is derived to model variations in total backscatter coefficient and extinction profiles in the visible and the near infrared (NIR). The profiles are used to estimate signal-to-noise ratio, laser-pulse energy, and wave-front measurement error with respect to backscatter strength, guidestar pulse length and altitude, and pixel noise. The results show that for a given wave-front measurement phase error (1) visible guidestars require less pulse energy for aerosol concentrations near background, where molecular backscatter dominates, and (2) for high aerosol loading following a major volcanic event, a NIR guidestar can reduce the energy requirement below that for visible sensing.
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Nahrstedt