Bromine in the tropical troposphere and stratosphere as derived from balloon-borne BrO observations

The first tropospheric and stratospheric (4 to 33 km) BrO profile is presented for the inner tropics derived from balloon-borne DOAS (Differential Optical Absorption Spectroscopy) measurements. In combination with photochemical modelling, total stratospheric inorganic bromine (Bry) is deduced to be (21.5±2.5) ppt in 4.5-year-old air, probed in 2005. We derive a total contribution of (5.2±2.5) ppt from brominated very short-lived substances and inorganic product gases to stratospheric Bry Tropospheric BrO was found to be y in the lower stratosphere. Bromine source gas measurements performed 10 days earlier Laube et al., 2008, indicate a lower Bry of (17.5±0.4) ppt. Potential reasons for this discrepancy are discussed.