Analysis of SAGE II ozone of the middle and upper stratosphere for its response to a decadal-scale forcing

Abstract

Abstract.Stratospheric Aerosol and Gas Experiment (SAGE II) Version 6.2 ozone profiles are analyzed for their decadal-scale responses in the middle and upper stratosphere from September 1991 to August 2005. The profile data are averaged within twelve, 20 • -wide latitude bins from 55 • S to 55 • N and at twelve altitudes from 27.5 to 55.0 km. The separate, 14-yr data time series are analyzed using multiple linear regression (MLR) models that include seasonal, 28 and 21-month, 11-yr sinusoid, and linear trend terms. Proxies are not used for the 28-mo (QBO-like), 11-yr solar uv-flux, or reactive chlorine terms. Instead, the present analysis focuses on the periodic 11-yr terms to see whether they are in-phase with that of a direct, uv-flux forcing or are dominated by some other decadal-scale influence. It is shown that they are inphase over most of the latitude/altitude domain and that they have max minus min variations between 25 • S and 25 • N that peak near 4% between 30 and 40 km. Model simulations of the direct effects of uv-flux forcings agree with this finding. The shape of the 11-yr ozone response profile from SAGE II also agrees with that diagnosed for the stratosphere over the same time period from the HALOE data. Ozone in the middle stratosphere of the northern subtropics is perturbed during 1991-1992 following the eruption of Pinatubo, and there are pronounced decadal-scale variations in the ozone of the upper stratosphere for the northern middle latitudes presumably due to dynamical forcings. The 11-yr ozone responses of the Southern Hemisphere appear to be free of those extra influences. The associated linear trend terms from the SAGE II analyses are slightly negative (−2 to −4%/decade) between 35 and 45 km and nearly constant across latitude. This finding is consistent with the fact that ozone is estimated to have decreased by no more than 1.5% due to the increasing chlorine from mid-1992 to about 2000 but with little change Correspondence to: E. Remsberg (ellis.e.remsberg@nasa.gov) thereafter. It is concluded that a satellite, solar occultation measurement provides both the signal sensitivity and the vertical resolution to record the stratospheric ozone response to the forcing from the solar uv-flux, as well as those due to any other long-term changes.

Reevaluation of stratospheric ozone trends from SAGE II data using a simultaneous temporal and spatial analysis

“…The data used for the QBO proxy come from equatorial data up to an altitude of ∼ 32 km. However, it has been shown that the frequencies at which the QBO oscillates are different at higher latitudes than at the Equator (Tung and Yang, 1994) and at higher altitudes (Remsberg and Lingenfelser, 2010). While the use of a proxy is better than simply using oscillating functions of different frequencies (since the QBO changes frequencies over time) and the use of orthogonal functions allows for the change in amplitude and phase of the response, it cannot account for the change in frequencies.…”

Solar response in tropical stratospheric ozone: a 3-D chemical transport model study using ERA reanalyses

“…15) showed that SAGE II and HALOE solar responses (averaged between 25 • S-25 • N) are quite similar. However, it is also important to remember that both Remsberg (2008) and Remsberg and Lingenfelser (2010) use relatively short time series in their analysis.…”

The decrease in mid-stratospheric tropical ozone since 1991

“…The N 2 O mixing ratio at 30 km from 30 • S to 30 • N was found to be no more than 2 % G. E. Nedoluha et al: The decrease in mid-stratospheric tropical ozone 4217 higher at solar minimum compared to solar maximum, and no more 4 % from 30 to 60 • N and 30 to 60 • S. Schmidt et al (2010) used the HAMMONIA general circulation and chemistry model, and found an equatorial O 3 sensitivity of ∼ 1.4 ± 0.4 % 100 −1 solar flux units (sfu), where the difference between the 1989 solar max and the 1986 solar min is 166 sfu. The study of Remsberg and Lingenfelser (2010) shows a 3 % ozone maximum-minimum response to the solar cycle at ∼ 35 km (∼ 7 hPa) from the SAGE II measurements, with results from the HALOE measurements and from model calculations showing a smaller ozone response to the solar cycle. As discussed in Hood and Soukharev (2006), NO y in the upper stratosphere is also affected by the solar cycle.…”