Response of ozone to short‐term variations in the solar ultraviolet irradiance: 2. Observations and interpretation

Abstract

An analysis of the response of middle atmospheric ozone to short‐term variations in the solar ultraviolet irradiance is presented. Measurements of ozone from the Solar Mesosphere Explorer (SME) ultraviolet spectrometer (UVS) are compared to calculations of a one‐dimensional, radiative‐photochemical model of the upper stratosphere and lower mesosphere. SME UVS measurements in the 0.1‐ to 1‐mbar range suggest that tropical ozone responds to solar rotational variation when analyzed using both frequency and time domain techniques. Three periods during 1982 and 1983 were selected for the analysis. The solar irradiance during each period exhibited different spectral characteristics. A significant 27‐day variation in the solar irradiance at 205 nm was measured during mid‐1982, with an amplitude of 2.5%. Observations of ozone near the stratopause during this period showed a corresponding variation, with a 1.3% amplitude. Analysis of ozone variations at extratropical latitudes revealed different periodicities that were not correlated with solar variations. The amplitude of the measured response is, in all cases, systematically larger than theoretical calculations but is nonetheless in agreement when uncertainties in the analysis are considered. However, the observed phase lag of ozone with respect to the solar UV variations is generally not in accord with model predictions.