An analysis is presented of 3.8 years of Solar Mesosphere Explorer (SME) IR ozone data and 4.3 years of Nimbus 7 stratosphere and mesosphere sounder temperature data for the purpose of estimating and characterizing the zonal mean response of the mesosphere to solar ultraviolet variations occurring on the solar rotation time scale. In agreement with an earlier study by Keating et al. (1987) the maximum low-latitude ozone and temperature response amplitudes occur at essentially the same level (~0.06 mbar; approximately 68 km altitude). The ozone response is negative and occurs at nearly zero lag, while the peak temperature response is positive and occurs at a lag of 3 to 5 days. The derived ozone response sensitivities and phase lags in the lower mesosphere merge smoothly with those previously determined for the upper stratosphere using independent satellite data sets. Some evidence for a weak negative ozone response near 75 km at high winter latitudes is also obtained. Temperature perturbations at low latitudes that correlate with solar ultraviolet flux variations are connected in phase with those occurring at higher latitudes in the winter hemisphere, suggesting the existence of a dynamical component of the mesospheric response.

The coexistence of positive temperature and negative ozone response maxima at the same level (~68 km) indicates strong coupling between photochemical and thermal components of the response. The negative ozone response can potentially be explained by a combination of temperature feedback from the observed temperature response and increased Lyman α dissociation of water vapor (followed by HOx destruction of ozone). The positive temperature response cannot be due to ozone radiative heating since the ozone perturbation is negative. However, other heating terms, including those due to exothermic chemical reactions, are known to contribute to the mesospheric heat budget. In particular, HOx chemical heating (mainly from H+O3→OH+O2) will increase with ozone destruction and may therefore be a likely candidate mechanism. ¿American Geophysical Union 1991