Scattering corrections to visible and infrared transmittance measurements in falling snow

Document Type

Article

Publication Date

9-22-1983

Abstract

A method is presented for extracting corrected extinction coefficients from transmittance measurements in a scattering atmosphere, by computing the unscattered, first-order scattered, and second-order scattered contributions to received power. These computations are based on the optical phase function of the scattering particles and on the optical characteristics of the measuring system. The method is applied to transmittance measurements in falling snow, which were made simultaneously at 0.6328, 1.06, 3 to 5, and 8 to 12 micrometers by using two laser transmissometers and an infrared transmissometer on a one kilometer horizontal outdoor path. The optical phase function of the snow crystals was measured at the same time as the snow transmittance measurements, by using a polar nephelometer with a 0.6328 micrometer light source. Models based on geometrical optics was then fitted to the measured data to generate a continuous function from 0 to 180 degrees, and this model was also used to extend the phase function to 1.06, 3 to 5, and 8 to 12 micrometers. Extinction coefficients extracted by this method from the 1.06, 3 to 5, and 8 to 12 micrometer transmittance data are compared to those at 0.6328 micrometers. © 1983 SPIE.

Publication Title

Proceedings of SPIE - The International Society for Optical Engineering

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