Wet chemical surface ozone measurements during POLARSTERN cruise ANT-III/2 (PS06) in 1984@en

On the outward journey an ozone minimum was encountered at the ITCZ, as is typical for high levels of solar radiation and low vertical exchange. Under such conditions, ozone can be depleted by photolysis, but cannot be replaced due to weak vertical exchange. On the return voyage, two ozone peaks occurred at and north of the ITCZ. According to Class and Ballschmiter (1986) who measured some organic trace gases, the ITCZ consisted of two branches found at 2°S and 2°N. The noticeable ozone peaks may have been caused by strong vertical exchange, with ozone being mixed down from the upper troposphere. In some cases, clear daily variations were recorded during the journey.