Stratospheric BrONO₂ observed by MIPAS

Abstract. The first measurements of stratospheric bromine nitrate (BrONO₂) are reported. Bromine nitrate has been clearly identified in atmospheric infrared emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Envisat satellite, and stratospheric concentration profiles have been determined for different conditions (day and night, different latitudes). The BrONO₂ concentrations show strong day/night variations, with much lower concentrations during the day. Maximum volume mixing ratios observed during night are 20 to 25 pptv. The observed concentration profiles are in agreement with estimations from photochemical models and show that the current understanding of stratospheric bromine chemistry is generally correct.