Climatology and trends of mesospheric (58–90 km) temperatures based upon 1982–1986 SME Limb scattering profiles

Abstract

Global observations of ultraviolet limb radiances from the Solar Mesosphere Explorer (SME) have been analyzed to obtain atmospheric temperature profiles over the altitude range 58–90 km. The temperature analysis is based upon vertical profiles of Rayleigh scattering, which are derived from the SME ultraviolet limb radiances. Comparisons are provided with lidar and Stratosphere and Mesosphere Sounder (SAMS) temperature observations at 65 km altitude, and with previous temperature climatologies of the mesosphere. SME monthly average temperature profiles are presented for 10° latitude intervals between 70°S and 70°N latitudes, over the January 1982 to September 1986 time period. The altitude resolution (∼4 km), latitudinal coverage (with 5° resolution), 5‐year term, and mesopause coverage of these temperature observations allow new insight into the average mesospheric temperature structure and unique observations of mesospheric temperature trends corresponding to the 1982–1986 solar maximum to solar minimum cycle. The SME temperature observations define large (10–30 K) semiannual oscillations of equatorial mesopause temperatures; mid‐latitude temperature inversions in the winter mesosphere accompanied by steep mesospheric temperature gradients at low latitudes, and −1.5 to +1 K/year trends, which suggest an intensification of these latitude‐dependent temperature gradients over the 1982–1986 period. The SME temperature trends are ∼4 times smaller than those reported by Mohanakumar (1985), Groves (1986), and Chanin et al. (1987) for solar cycle variations of temperatures in the altitude region 65–70 km.