A chemical ionization mass spectrometer was used to measure BrO and HOBr+Br-2 over the Tropical West Pacific Ocean within the altitude range of 1 to 15km, during the CONvective TRansport of Active Species in the Tropics (CONTRAST) campaign in 2014. Isolated episodes of elevated BrO (up to 6.6pptv) and/or HOBr+Br-2 (up to 7.3pptv) were observed in the tropical free troposphere (TFT) and were associated with biomass burning. However, most of the time we did not observe significant BrO or HOBr+Br-2 in the TFT and the tropical tropopause layer (TTL) above our limits of detection (LOD). The 1min average LOD for BrO ranged from 0.6 to 1.6pptv and for HOBr+Br-2 ranged from 1.3 to 3.5pptv. During one flight, BrO observations from the TTL to the extratropical lowermost stratosphere were used to infer a profile of inorganic bromine (Br-y). Based on this profile, we estimated the product gas injection of bromine species into the stratosphere to be 2pptv. Analysis of Br-y partitioning further indicates that BrO levels are likely very low in the TFT environment and that future studies should target the measurement of HBr or atomic Br.
