While earlier tests performed in the Arctic had demonstrated that water vapor was a key component in creating the "free-radical" compounds that break down ozone, Anderson said the latest finding is much more troubling, because it suggests the process can happen at much higher temperatures than initially suspected.
"The bottom line is that if you increase the water vapor concentration, you actually increase the threshold temperature for executing this chemical conversion from the stable forms of chlorine to the free radical form," Anderson said. "If the amount of water vapor and the temperature over the U.S. satisfies the conditions for rapid conversion of inorganic chlorine to this free-radical form, we've got a real problem, because the chemistry is identical to what we previously demonstrated is taking place over the Arctic."
Also surprising, he added, was the realization that, to throw water vapor high into the atmosphere, storms needn't be unusually large.
"We have hundreds of measurements world-wide addressing the photochemical structure controlling ozone, but only a limited number of flights over the U.S. in summer," he said. "The flights were studying average storms over the middle-west, and of the 20 observations we made over the U.S., about half demonstrated significant penetration into the stratosphere," he said.
The next step in the research, Anderson said, is to conduct a series of tests to confirm whether the free-radical form of chlorine and bromine are present in the stratosphere at significantly elevated levels in the presence of convectively-injected water vapor.
"In my mind, this is not just a broad public health issue," Anderson said. "This is about actually being able to step out into the sunlight it's about your children and your children's health. Of course, we don't know how rapidly the frequency and intensity of these storms will increase, so we can't place a time scale on this problem,
|Contact: Peter Reuell|