
In the polar vortex regions HCl is
converted to ClO which destroys ozone
6.28.2006
When CFC's are photolyzed, the chlorine mostly goes to form HCl. Thus monitoring HCl tells us about ozone loss processes and the recovery of the ozone layer. The top slide shows how HCl is converted into ozone destroying ClO (also measured by MLS) during the polar winter. In the Antarctic ozone hole, once ozone is gone, the free chlorine reacts with methane rapidly forming HC. In the northern winter, not all the ozone is destroyed so the recovery to HCl is not as rapid, both HCll and ClONO2 form.
CFCs were banned in the 1980's so the chlorine input to the stratosphere has decreased. The lower graph shows the slow decrease in HCl with time as chlorine is leaving the stratosphere.