The Upper Atmosphere Research Satellite (UARS) continued to provide evidence in 1994 of ozone loss in the wintertime polar regions due to chemical destruction by stratospheric chlorine.
The UARS payload contains eight instruments which together observe solar radiation, particles and fields, atmospheric temperatures, winds, and trace gas concentrations. As it has since 1991, UARS made global measurements of stratospheric ozone and chlorine monoxide (the predominant form of reactive chlorine that destroys ozone).
Data have shown ozone decreases and high concentrations of chlorine monoxide in both the northern and southern polar regions, explained Dr. Joe Waters. A collaboration of UARS instrument and theoretical teams published results in the Aug. 11, 1994, issue of Nature magazine of a detailed investigation into the ozone decrease observed in the Arctic during winter 1992-93.
"The essence of what we did," reported Dr. Richard Zurek, principal investigator of the theoretical investigation, "is establish that the ozone decrease was not caused just by the transport of ozone-poor air." This was established in part using the distributions of long- lived trace gases measured by Lockheed's Cryogenic Limb Array Etalon Spectrometer on UARS. Together with observations that chlorine was mostly in chemically reactive forms, the analysis provided direct evidence that the stratospheric ozone decrease observed during February and early March 1993 was due to chemical destruction by this reactive chlorine.