Further analyses of the decadal-scale responses and trends in middle and upper stratospheric ozone from SAGE II and HALOE

Abstract. Stratospheric Aerosol and Gas Experiment (SAGE II) Version 6.2 ozone profiles are analyzed for their decadal-scale responses and linear trends in the middle and upper stratosphere from 1984 through 1998. The results are compared with those of SAGE II and of the Halogen Occultation Experiment (HALOE) for 1991–2005, reported previously by Remsberg and Lingenfelser (2010). The regression model fit to the data includes a periodic 11- term, and it is in-phase with that of the 11-yr solar uv-flux throughout most of the latitude/altitude domain of the middle and upper stratosphere. Max minus min responses for the upper stratosphere are of order 2% from the HALOE time series that are in terms of mixing ratio versus pressure. Max minus min responses are of order 4% from SAGE II in terms of number density versus altitude and for both 1984–1998 and 1991–2005, even though the concurrent linear trend term coefficients are much different for the two time spans. However, the analyzed 11-yr response from the SAGE II data of 1984–1998 lags that of the uv-flux by 1 to 2 yr in the tropical middle stratosphere, most likely due to the effects of ENSO forcings that are not represented in the regression models. The linear ozone trends in the upper stratosphere for 1991 to 2005 are of the order of −2 to −3%/decade from SAGE II and 0 to −1%/decade from HALOE. Those differences in the ozone trends must be principally due to the associated temperature trends for the analyzed data.