Ozone profile retrieval from Stratospheric Aerosol and Gas Experiment (SAGE III) limb scatter measurements

Abstract

The ability of SAGE III to retrieve the ozone vertical distribution within the atmosphere from limb scatter measurements is being investigated. The sunlight scattered by atmospheric gases and particulates (aerosol and clouds) and the Earth's surface is measured and spectrally dispersed by the SAGE III high vertical resolution spectrometer. The spectral data are shown to contain sufficient information to retrieve ozone density from 10 km (or cloud top) to 50 km at a resolution of about 1 km using ultraviolet and visible channels. Since SAGE III was not designed to operate in limb scatter mode, the radiance measurements are contaminated with significant stray light, and a method had to first be developed and implemented to deconvolve instrumental effects from the data. Furthermore, SAGE III has limited attitude determination capability, and tangent altitude registration has to be derived mostly from measured radiance profiles. Two retrieval algorithms were implemented to infer ozone profiles from measured radiance data: the first one is based on the wavelength triplet method, and the second one uses the multiple linear regression technique. Retrieved ozone profiles are shown for a series of cases and compared with available correlative data measured by ozone sondes, SAGE III in occultation mode, and OSIRIS.