Surface ozone depletion episodes

Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Abstract Episodes of ozone depletion in the lowermost Arctic atmosphere (0–2 km) at polar sunrise have been intensively studied at Alert, Canada, and are thought to result from catalytic reactions involving bromine. Recent observations of high concentrations of tropospheric BrO over large areas of the Arctic and Antarctic suggest that such deple-5 tion events should also be seen by ozonesondes at other polar stations. An examination of historical ozonesonde records shows that such events occur frequently at Alert, Eureka and Resolute, but much less frequently at Churchill and at other stations. The differences appear to be attributable to differences in surface meteorology. The long record at Resolute shows depletions since 1966, but with an apparent increase in their 10 frequency since about 1985. This is surprising, since the Br involved in the depletion mechanism is believed to be entirely of natural origin.