York scientists help confirm big drop in earth’s ozone

Researchers at York’s Department of Earth and Space Science & Engineering, contributed to a report published on March 2 of a significant decrease in the ozone layer above the earth’s northern latitudes.

Craig Haley

Co-author Craig Haley, a doctoral candidate and member of a York team that studies earth’s upper atmosphere, said the study released by the University of Colorado at Boulder included information from the Canadian-built OSIRIS (Optical Spectrograph and InfraRed Imager System) instrument that confirmed what other teams around the world also observed: up to a 60-per-cent drop in ozone that scientists believe was caused by a solar storm in October 2003 followed by high arctic winds in the spring of 2004.

Right: Craig Haley, researcher in York’s Department of Earth and Space Science & Engineering

OSIRIS is onboard the Odin satellite, a joint project between Canada, Sweden, France and Finland, launched in February 2001, for a planned two-year flight that is now entering its fifth year. OSIRIS was designed and built by Routes AstroEngineering, a space-engineering firm based in Kanata, Ont. Professor E.J. Llewellyn at the University of Saskatchewan is the principal investigator of OSIRIS, and professors at York, Trent University and the University of Toronto are members of the OSIRIS Science Team.

The York team has been primarily involved in the analysis of OSIRIS measurements to produce vertical profiles of the concentration of ozone and nitrogen dioxide in the stratosphere. The Boulder study used that data to show that the OSIRIS results are consistent with the results from other satellites indicating there was a dramatic increase in the amount of nitrogen dioxide in the upper stratosphere that led to ozone reductions of up to 60 per cent at about 40 km at northern high latitudes in spring 2004. This unpredicted and unprecedented decline was related to a combination of the unique stratosphere weather and solar activity of late 2003 and early 2004. Haley said although the study results are not conclusive, they do suggest that the conditions in spring 2004 are at least partially related to the Halloween solar storms of 2003.

“The results of this study do not affect our understanding of the past and present situation of stratospheric ozone depletion, which is largely due to the release of CFCs into the atmosphere” Haley said. “What the study illustrates is that there is a source of significant ozone destruction that is not currently included in the models used to predict the future situation.”

Haley said scientists agree we are at a time where ozone depletion is decreasing and perhaps beginning recovery, thanks largely to the Montreal Protocol and amendments. “The difficulty is that the extrapolation into the future from this point is very sensitive to the conditions that are included in the extremely complicated atmospheric models that are required. The more we understand the atmospheric effects from natural and human-induced causes, the more accurately we can predict the future trend,” he added.

The media release on the publication of the study is available at the American Geophysical Union Web site. The study was published in the March 2 issue of Geophysical Research Letters.