February 28, 2007
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A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 12, NUMBER 2, FEBRUARY 1999
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.
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.
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