On the response of Halogen Occultation Experiment (HALOE) stratospheric ozone and temperature to the 11-year solar cycle forcing

Results are presented on responses in 14-year (1991-2005) time series of stratospheric ozone and temperature from the Halogen Occultation Experiment (HALOE) of the Upper Atmosphere Research Satellite (UARS) to a solar cycle (SC-like) variation. The ozone time series are for ten, 20-degree-wide, latitude bins from 45 degrees S to 45 degrees N and for thirteen "half-Umkehr'' layers of about 2.5 km thickness and extending from 63 hPa to 0.7 hPa. The temperature time series analyses were restricted to pressure levels in the range of 2 hPa to 0.7 hPa. Multiple linear regression ( MLR) techniques were applied to each of the 130 time series of bin-averaged, sunrise plus sunset ozone points over that latitude/pressure domain. A simple, 11-year periodic term and a linear trend term were added to the final MLR models after their seasonal and interannual terms had been determined. Where the amplitudes of the 11-year terms are significant, they are in phase with those of the more standard proxies for the solar UV flux. The maximum minus minimum response for ozone is on the order of 2 to 3% from about 2 to 5 hPa and for the latitudes of 45 degrees S to 45 degrees N. There is also a significant maximum minus minimum response on the order of 1 K for temperature between 15 degrees S and 15 degrees N and from 2 to 0.7 hPa. The associated linear trends for ozone are near zero in the upper stratosphere. It is noted, however, that effects of the changes in total chlorine during this 14-year period were not accounted for explicitly and that their omission can be a confounding effect for both the analyzed solar cycle responses and the linear terms, especially for tropical upper stratospheric ozone. It is concluded that the solar occultation technique of HALOE provided adequate sampling and sufficient vertical resolution for obtaining the solar cycle response in stratospheric ozone.