Ozone and temperature decadal responses to solar variability in the stratosphere and lower mesosphere, based on measurements from SABER on TIMED

Abstract

We have derived ozone and temperature responses to solar variability over a solar cycle, from 2002 to 2014 at 20-60km and 48°S-48°N, based on data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. Simultaneous results for ozone and temperature with this kind of spatial coverage have not been previously available, and they provide the opportunity to study correlations between ozone and temperature responses. In previous studies, there has not been general agreement on the details or, at times, even the broad behavior of the responses to decadal solar variability. New results from a different dataset should supply new information on this important and interesting subject. A multiple regression is applied to obtain responses as a function of the solar 10.7cm flux. Positive responses mean that they are larger at solar maximum than at solar minimum of the solar cycle. Both ozone and temperature responses are found be positive or negative, depending on location. Generally, from ~25 to 60km, the ozone and temperature responses are mostly out of phase (negatively correlated) with each other as a function of solar variability, with some exceptions in the lower altitudes. These negative correlations are maintained even though the individual ozone (temperature) responses can change signs as a function of altitude and latitude, because the corresponding temperature (ozone) responses change signs in step with each other. From ~50 to 60km, ozone responses are relatively small, varying from ~-1 to ~2%100sfu-1 (solar flux units), while temperature responses can approach ~2°K100sfu-1. From ~25 to ~40km, the ozone responses have become mostly positive at all latitudes and approach a maximum of ~5%100sfu-1 near the Equator and ~30-35km. In contrast, at low latitudes, the temperature responses have become negative but also reach a local maximum (near 32km) in magnitude. The ozone and temperature responses remain mostly out of phase, with isolated exceptions at midlatitudes between ~25 and 45km. The general negative correlations are consistent with the idea that photochemistry is more in control in the upper stratosphere and lower mesosphere. The correlation coefficients between the solar 10.7cm flux and the ozone and temperature themselves from 2002 to 2014 are positive (negative) in regions where the responses are positive (negative). This supports our results since the correlations are independent of the multiple regression used to derive the responses. We also compare with previous results.