In the current study, Yang, Cunnold and their co-authors reached their conclusions based on satellite and ground-based atmospheric ozone measurements. They analyzed atremendous amount of data from three extremely accurate NASA satellite's instruments(SAGE I and II and HALOE) that began collecting data in 1979 and continued until 2005,with the exception of a three-year period in the early 1980s. Ground-based ozone measurements taken by NASA and NOAA from 1979 to 2005 and balloons provided essential complementary data for the study, Yang said. The satellites and the balloonsmeasured ozone levels by atmospheric region. The ground-based data recorded measurements for the total ozone column.
"The ground-based measurements were especially important for the lower atmosphere because satellites can have difficulty in sensing the lowest regions," Yang said.
Salawitch, a senior research scientist at NASA's Jet Propulsion Laboratory, noted: "Our study provides a quantitative measure of a key fingerprint that is lacking in earlier studies -- the response of the ozone layer as function of height. We reconcile the height-dependent response with observations from other instruments that record variations in total-column ozone".
To accurately attribute the ozone level changes to the Montreal Protocol, researchers had to account for long- and short-term natural fluctuations in ozone concentration, Cunnold noted. One such fluctuation is an 11-year solar cycle, and ano
Source:Georgia Institute of Technology Research News