The possible detection of OBrO in the stratosphere

Jean-Baptiste Renard (1) , Michel Pirre (2) , C Robert (2) , Daniel Huguenin (3)

1 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
2 LPCE - Laboratoire de physique et chimie de l'environnement
3 ObsGE - Observatoire Astronomique de l'Université de Genève

The analysis of spectral residua recorded at night by the balloon-borne AMON (Absorption par Minoritaires Ozone et Nox) UV-visible spectrometer during five stratospheric flights at middle and high latitudes shows that some absorption features remain in the 475-550 nm range, while the Rayleigh, aerosol, ozone, and NO2 contributions are subtracted. The data reduction relating to these spectral lines is presented for the flight of February 26, 1997, at Kiruna (Sweden) inside the polar vortex. A good agreement exists between these unknown absorption features and those attributed to OBrO during recent laboratory measurements. The results of measurements from the other AMON flights are also presented. Assuming a OBrO cross section maximum similar to that of OC10, an upper limit for the OBrO mixing ratio is found to be around 20 pptv at midlatitude, implying that OBrO would be the principal bromine species at night in the middle stratosphere. At high latitude the OBrO mixing ratio decreases, particularly in the presence of OC10 (also measured by AMON). The results are contradictory to current knowledge and, if confirmed, could argue for major revision of the assumed bromine chemistry in the stratosphere.

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]; Geophysics [physics.geo-ph]

Jean-Baptiste Renard, Michel Pirre, C Robert, Daniel Huguenin. The possible detection of OBrO in the stratosphere. Journal of Geophysical Research: Atmospheres, 1998, 103 (D19), pp.383-408. ⟨10.1029/98JD01805⟩. ⟨insu-02879280⟩