K. Pfeilsticker et al., Lower stratospheric organic and inorganic bromine budget for the Arctic winter 1998/99, GEOPHYS R L, 27(20), 2000, pp. 3305-3308
In the Arctic winter 1998/99, two balloon payloads were launched in a co-or
dinated study of stratospheric bromine. Vertical profiles (9-28 km) of all
known major organic Br species (CH3Br, C2H5Br, CH2BrCl, CHBrCl2, CH2Br2, CH
Br2Cl, CHBr3, H1301, H1211, H2402, and H1202) were measured, and total orga
nic Br (henceforth called Br-y(org)) originating from these organic precurs
ors was inferred as a function of altitude. This was compared with total in
organic reactive Br (henceforth called Br-y(in)) derived from spectroscopic
BrO observations, after accounting for modeled stratospheric Br-y partitio
ning. Within the studied altitude range the two profiles differed by less t
han the estimated accumulated uncertainties. This good agreement suggests t
hat the lower stratospheric budget and chemistry of Br is well understood f
or the specified conditions. For early 1999 our data suggest a Br-y(in) mix
ing ratio of 1.5 ppt in air just above the local Arctic tropopause (similar
to 9.5 km), whilst at 25 km in air of 5.6 yr mean age it was estimated to
be 18.4(+1.8/-1.5) ppt from organic pr cursor measurements, and (21.5+/-3.0
) ppt from BrO measurements and photochemical modelling, respectively. This
suggests a Br-y(in) influx of 3.1(-2.9/+3.5) ppt from the troposphere to t
he stratosphere.