In situ observations of BrO over Antarctica: ER-2 aircraft results from 54°S to 72°S latitude

The distribution of BrO inside the chemically perturbed region defined by greatly elevated ClO abundances was different from that found just outside. Inside, the BrO mixing ratio was 6.1 ± 1.1 pptv above the 440 K potential temperature surface, 4.7 ± 2.0 pptv between the 400 and 440 K surfaces, and less than 4 pptv below the 400 K surface. At high latitudes outside the chemically perturbed region, the BrO mixing ratio was 5.4 ± 1.4 pptv near the 450 K surface, but decreased to 2.9 ± 1.2 pptv at the 420 K surface. Away from the south polar region, at latitudes between 47°S and 37°N and potential temperatures between 435 and 500 K (18.5- to 20.7-km altitude), the BrO mixing ratio was 0.5-3.0 pptv. -from Authors