EOS Microwave Limb Sounder observations of upper stratospheric BrO: Implications for total bromine

This paper describes new total stratospheric inorganic bromine (Br(y)) abundance estimates inferred from the first global observations of upper stratospheric BrO, made by the EOS Microwave Limb Sounder on the Aura satellite. Our 'best estimate' of total upper stratospheric bromine loading (based on JPL-2002 kinetics with the addition of a BrONO(2)+O reaction) is 18.6 +/- 5.5 pptv, for the period September 2004 to August 2005, from 55 degrees S to 55 degrees N. This implies a contribution of 3.0 +/- 5.5 pptv from sources other than long lived CH(3)Br and halons. The possibility of such other sources has been raised by balloon, aircraft and satellite observations of BrO in the lower and middle stratosphere. These upper stratospheric observations provide new information to help resolve the current uncertainty in stratospheric bromine loading. The abundance of bromine, particularly in the lower stratosphere, is a significant factor in the budget of stratospheric O(3).