Heterogeneous chemistry of bromine species in sulfuric acid under stratospheric conditions

The first‐order loss rate coefficients for BrONO 2 on 45, 60, and 70 wt% sulfuric acid solutions were measured in a wetted‐wall flow tube reactor. The BrONO 2 reactive uptake coefficients were >0.2 and HOBr was the product. When HCl was added to the acid, production of HOBr was still observed but the main product was BrCl. Based on these observations it is concluded that the conversion of BrONO 2 to active forms such as HOBr and BrCl on sulfate aerosols in the stratosphere is very rapid. The efficiency of the hydrolysis of BrONO 2 suggests that, even for non‐volcanic conditions, much of the BrONO 2 in the stratosphere can be converted to HOBr at night.