Measurements of mixing ratio profiles of stratospheric bromine monoxide (BrO) were made using observations of BrO rotational line emission at 650.179 GHz by a balloon-borne SIS (superconductorinsulator-superconductor) submillimeterwave heterodyne limb sounder (SLS). The balloon was launched from Ft. Sumner, New Mexico (34◦ N) on 22 September 2011. Peak mid-day BrO abundance varied from 16 ± 2 ppt at 34 km to 6 ± 4 ppt at 16 km. Corresponding estimates of total inorganic bromine (Bry ), derived from BrO vmr (volume mixing ratio) using a photochemical box model, were 21 ± 3 ppt and 11 ± 5 ppt, respectively. Inferred Bry abundance exceeds that attributable solely to decomposition of long-lived methyl bromide and other halons, and is consistent with a contribution from bromine-containing very short lived substances, BrVSLS , of 4 ppt to 8 ppt. These
y results for BrO and Bry were compared with, and found to be in good agreement with, those of other recent balloon-borne and satellite instruments.