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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999

FROM VOLUME 12, NUMBER 2, FEBRUARY 1999

JOURNAL ARTICLES...
TROPOSPHERIC BROMINE

Item #d99feb16

“Evidence for Bromine Monoxide in the Free Troposphere During the Arctic Polar Sunrise,” C. T. McElroy, C. A. McLinden, and J. C. McConnell,Nature 397, 338-341 (Jan. 28, 1999).

Dramatic ozone losses are observed each spring in the troposphere over large areas of the Arctic, probably caused by catalytic degradation of ozone by BrO derived from bromine released from sea salt in the snow pack. Satellite observations have measured large enhancements of BrO in the Arctic troposphere. Now high-altitude aircraft indicate that the BrO is transported up into the planetary boundary layer and the free troposphere above it by convection over areas of open water among the pack ice. Water and ice particles are also transported upward, providing surfaces for the heterogeneous reactions that allow BrO to catalyze ozone decomposition.

Item #d99feb17

“DOAS Measurements of Tropospheric Bromine Oxide in Mid-Latitudes,” Kai Hebestreit et al., Science 283, 55-57 (Jan. 1, 1999).

Localized, high BrO concentrations were observed at the Dead Sea in Israel and correlated with low boundary-layer ozone mixing ratios. The highest BrO concentration was 86 ± 10 ppt, three times the concentrations measured in polar regions. The concentration varied diurnally with wind direction. Correllation of BrO concentration, wind speed, and wind direction indicated extended salt pans in the Dead Sea Valley to be the the source of the bromine; industrial sources were ruled out because they were too distant. Similar salt pans are found in many other locations around the world.