Solar Effects in the UARS-HALOE Ozone Dataset

A set of 14-year time series of ozone from the HALOE experiment of the UARS satellite has been analyzed for seasonal, interannual, and 11-yr solar cycle (SC) effects. The ozone time series were obtained for 40S to 40N in 10-degree wide latitude bins and for 12 “half-Umkehr” layers of about 2.5 km thickness and extending over the range of 22.4 hPa to 0.35 hPa. Multiple linear regression (MLR) techniques were applied to each of those 108 separate time series of about 200 zonally-averaged, sunrise plus sunset points. The average point spacing is about 25 days, which is an adequate sampling rate for resolving the SAO and longer cycles. QBO and sub-biennial cycles were also found throughout this domain of latitude and pressure-altitude. A simple sinusoidal, SC-like term of 11-yr period was fit to the time series residuals after accounting for the seasonal (annual and semi-annual) and interannual terms. The phase of this SC-like term was noted, and in almost all cases it was in-phase with that of the more standard proxies for the solar uv-flux. The SC-like response for upper stratospheric ozone agrees well with that reported by others from fairly simple models that include the maximum-to-minimum forcing of the 11-yr variations for the uv-flux. In the northern hemisphere subtropics the diagnosed SC-like response is enhanced from 7 hPa to 20 hPa, due to additional decadal-scale, dynamical interactions of the QBO and sub-biennial cycles.