Trends in Stratospheric Ozone Derived from Merged Odin-OSIRIS and SAGE II Satellite Observations

Abstract:

Stratospheric ozone profile measurements from the Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite (2001–Present) are merged with those from the Stratospheric Aerosol and Gas Experiment (SAGE) II satellite instrument (1984–2005) to calculate decadal trends in stratospheric ozone between 60°S and 60°N. A multi-instrument, multi-decade, deseasonalized and merged stratospheric ozone record (1984–present) is produced by analyzing the measurements during the operational overlap of both satellites (2001–2005). The deseasonalized monthly time series is fit using linear regression with six non-linear predictor basis functions: three quasi-biennial oscillation proxies, the El Niño- Southern Oscillation index, a solar activity proxy, and the NCEP pressure at the tropical tropopause; and two linear trends: before and after 1997, which give the decadal trends in ozone. From 1984–1997, statistically significant negative trends of 5–10% per decade exist throughout the stratosphere (30–50 km). From 1997–present, statistically significant recovery rates of 3–8% per decade exist throughout most of the stratosphere. Below 22 km and between 40°S–40°N a negative trend is measured before and after 1997. The recovery is not significant in the tropical stratosphere between 25–35 km.