Trend analysis of total ozone data for turnaround and dynamical contributions

Abstract

Statistical trend analyses have been performed for monthly zonal average total ozone data from both TOMS and SBUV satellite sources and ground‐based instruments over the period 1978–2002 for detection of a “turnaround” in the previous downward trend behavior and hence evidence for the beginning of an ozone recovery. Since other climatic and geophysical changes can impact ozone behavior and can influence the detection of turnaround and recovery, we also focus on accounting for ozone variations that may be ascribed to various physical and chemical influences. Thus we include in the statistical trend modeling and analysis the effects of various dynamical and circulation variations in the atmosphere, including those associated with the quasibiennial oscillation (QBO), Arctic Oscillation (AO) and Antarctic Oscillation (AAO), and Eliassen‐Palm (EP) flux influences, as well as influences of solar cycle. A notable result of the analysis is that for latitude zones of 40° and above in both hemispheres, large positive and significant estimates of a change in trend (since 1996) are obtained (on the order of 1.5 to 3 DU per year). The dynamic index series, AO/AAO and EP flux, are found to have a substantial influence on total ozone for these higher latitudes, and significant influences of lesser magnitude are also found for lower latitudes. The feature of positive significant change in trend in total ozone over recent years, however, is obtained both without and with the dynamical index terms included in the statistical models.