| A method has been developed to retrieve mesospheric temperatures in the 65--90 km altitude range from satellite observations made by the Wind Imaging Interferometer (WINDII) aboard the Upper Atmosphere Research Satellite (UARS). Retrieved temperatures are derived from Rayleigh scattered sunlight measurements observed at a wavelength band centered at 553 nm. Integrated line-of-sight radiance observations are inverted to tangent height volume scattering profiles which are proportional to atmospheric density. Once vertical profiles of relative density are recovered, absolute temperature profiles are calculated using a technique derived from established Rayleigh lidar retrieval methods. Sources for error have been identified and typical temperature uncertainty values are determined to be less than 2.5%, 5.5% and 13% for altitudes 70 km, 80 km and 90 km, respectively. A thorough comparison of the derived WINDII temperatures is performed against a number of satellite and ground-based campaigns. In particular, they are compared against temperatures from ground-based lidar, falling spheres, satellite instruments including several others also aboard UARS, and against several common atmospheric models. The data analyzed in this study consist of spring equinox observations in March and April 1992/1993, summer solstice data in July 1992/1993 and winter solstice data in December 1992/1993 and January 1993/1994. The results of the comparisons show that WINDII temperatures are in reasonable to excellent agreement with a number of established temperature studies. In particular, July northern hemisphere monthly averaged temperatures show that characteristics of the mesopause obtained by WINDII are in very good agreement with other measurements. By providing a detailed description of our temperature retrieval method, showing good comparative results of our work with other established data sets and determining the error bounds of our recovered temperatures, this study has shown that WINDII data can be used to confidently derive near-global temperatures of the upper mesosphere between 65--90 km. (Abstract shortened by UMI.)... |
