On the Recovery of Stratospheric Ozone

• Activity Number: 47
• Type: Topic Contributed
• Date/Time: Sunday, August 8, 2004 : 4:00 PM to 5:50 PM
• Sponsor: Section on Statistics and the Environment
• Author(s): Serge Guillas*+ and Michael L. Stein and Donald Wuebbles
• Companies: University of Chicago and University of Chicago and University of Illinois, Urbana-Champaign
• Keywords: ozone ; trend analysis

Abstract

Since the implementation of the international controls on ozone-depleting chemicals, an important focus in studies of stratospheric ozone has been on the detection of a turnaround in the downward trend. We model the trend using the University of Illinois at Urbana-Champaign 2-D (UIUC 2-D) chemical-transport model of the global atmosphere. We carry out a study in the spectral domain on a cohesive dataset from the SBUV(/2) satellite system at northern midlatitudes. We prove that the model is better at capturing the long-range correlation of the data than assuming a piecewise linear trend. In a second time, we compare several statistical trend models, based on a regression either on a piecewise linear trend, or on the Effective Equivalent Stratospheric Chlorine (EESC) with or without a constant halocarbon emissions run of the UIUC 2-D model. The fit is better with the EESC approach, and the estimate of the EESC regression coefficient is more precise with the help of the UIUC 2-D model. The smallest number of years necessary to detect a recovery is obtained when the EESC is considered in the analysis.