| This work attempts to relate the polar spring time O3 depletion in the boundary-layer to the annual geochemical cycle of reactive bromine in the Arctic. The cycle appears to have three stages: (1) the winter build up of Br- in the snow pack, (2) spring time bromine release to the boundary layer, and (3) the dissipation of bromine into the free troposphere at the end of spring. Using a box model, the proposed mechanism for the spring time release of bromine is demonstrated. The model highlights the feature of this mechanism---the auto-catalytic release of bromine from snow pack, initiated by a bromine seed. From observations it is known that the geochemical cycle for chlorine in the Arctic does not exhibit the seasonal variation shown for bromine. For this, the seasonally independent geochemical cycle proposed previously for Cl2 in the marine boundary layer is adopted to recycle HCl in the model. (Abstract shortened by UMI.)... |
