Latitudinal distribution of atmospheric methyl bromide: Measurements and modeling

Abstract

The global distribution of atmospheric methyl bromide (CH 3 Br) obtained from extensive new measurements of atmospheric CH 3 Br from latitude 82.5°N to 69.1°S, showed a small decrease from mid‐ to high‐latitudes, a gradient between the northern and southern hemispheres with a ratio of 1.2 to 1.3, and occasional high concentrations in the tropics. The observed data and modeled distributions of industrial CH 3 Br were used to apportion CH 3 Br between natural and industrial components for both hemisphere. We obtained an estimated man‐made contribution of 4.3 pptv and 2.3 pptv in the northern and southern hemispheres, respectively and a natural (non‐industrial) background concentration in both hemispheres of 6 pptv with a slight increase in the tropics.