Solar Mesosphere Explorer Near‐Infrared Spectrometer: Measurements of 1.27‐μm radiances and the inference of mesospheric ozone

Abstract

Ozone in the mesosphere is determined from observations made by the near‐infrared spectrometer experiment on the Solar Mesosphere Explorer satellite (SME) between 50 and 90 km over most latitudes at 3:00 P.M. local time. The spectrometer measures emission from O2(1Δg) at 1.27 μm that is primarily due to the photodissociation of ozone. The instrument consists of a parabolic telescope that limits the field of view to less than 0.1°, an Ebert‐Fastie spectrometer, and a passively cooled lead sulfide detector system. The limb radiances, measured as the spacecraft spins, are inverted, producing volume emission rate profiles from which ozone densities are inferred. The vertical resolution is better than 3.5 km. The calculation of ozone accounts for quenching and atmospheric transmission of both solar radiation and 1.27‐μm radiation. We have established the existence of a secondary maximum of ozone density near 80km. An error analysis shows that the effects of random errors in the data and in the analysis on the final ozone profile are less than 10% between 50 and 82 km.