Variability of extratropical ozone stratosphere–troposphere exchange using microwave limb sounder observations

Abstract

[1] The extratropical stratosphere-troposphere exchange (STE) of ozone from 2005 to 2010 is estimated by combining Microwave Limb Sounder ozone observations and MERRA reanalysis meteorological fields in an established direct diagnostic framework. The multiyear mean ozone STE is 275 Tg yr À1 and 214 Tg yr À1 in the Northern and Southern Hemispheres, respectively. The year-to-year variability is greater in the Northern Hemisphere, where the difference between the highest and the lowest annual flux is 15% of the multiyear mean compared with 6% in the Southern Hemisphere. Variability of lower stratospheric ozone and variability of the net mass flux both contribute to interannual variability in the Northern Hemisphere ozone flux. The flux across the extratropical 380 K surface determines the amount of flux across the extratropical tropopause, and the greatest seasonal variability of the 380 K ozone flux occurs in the late winter/early spring, around the time of greatest flux. Both the mass flux and the ozone mixing ratios on the 380 K surface show recurring spatial patterns, but interannual variability of these quantities and their alignment contribute to the ozone flux variability. The spatial and temporal variability are not well represented when zonal and/or monthly mean fields are used to calculate the ozone STE, although this results in a small high bias of the seasonal amplitude and annual magnitude. If the climatological variability over these 6 years is representative, the estimated number of years required to detect a 2 À 3% decade À1 trend in ozone STE using this diagnostic is 35 À 39 years.Citation: Olsen, M. A., A. R. Douglass, and T. B. Kaplan (2013), Variability of extratropical ozone stratosphere-troposphere exchange using microwave limb sounder observations,

Drivers of changes in stratospheric and tropospheric ozone between year 2000 and 2100

“…However, the inferred STE of 360 ± 14 Tg(O 3 ) yr −1 is lower than observational estimates, which range between 450 and 550 Tg(O 3 ) yr −1 (e.g. Gettelman et al, 1997;Olsen et al, 2001Olsen et al, , 2013, and the ACCENT and ACCMIP means of 552 ± 168 and 477 ± 96 Tg(O 3 ) yr −1 , respectively. Nevertheless, a comparison to these model intercomparisons is likely to be inadequate in this case -only three out of the six ACCMIP models that reported STE contained full stratospheric chemistry Young et al, 2013), while almost none of the ACCENT models contained this representation.…”

“…The results therefore emphasise the need for a good representation of STE in CCMs to simulate future tropospheric ozone. While models with simplified stratospheric ozone chemistry are unlikely to represent STE accurately (Olsen et al, 2013), this study achieves greater fidelity in its representation through the use of a CCM which contains a relatively sophisticated description of stratospheric and tropospheric chemistry and dynamics. Nonetheless, better constraints on observed estimates of STE are required to deduce whether modelled values are realistic; it is hoped that, with continued satellite observations of ozone in the upper stratosphere-lower stratosphere (e.g.…”

Analysis of 20 years of tropospheric ozone vertical profiles by lidar and ECC at Observatoire de Haute Provence (OHP) at 44°N, 6.7°E

“…Although STE drive a significant part of the short-term variability (Beekmann et al, 1994a;Ord oñez et al, 2007;Olsen et al, 2013;Neu et al, 2014), its role in ozone trend is less obvious (Colette and Ancellet, 2005;Skerlak et al, 2014). Recent studies in North America show that increased biomass burning (e.g.…”

Stratosphere-troposphere exchange and its specific features at extratropical latitudes

“…For example, M.A. Olsen et al [75] used the Aura satellite observations of ozone and obtained the average annual values of the total ozone flux through the surface of 380 K, namely, 275 and 214 ´ 10 9 kg/year for the Northern and Southern hemispheres, respectively.…”