Wednesday, 25 January 2017
4E (Washington State Convention Center )
Tropospheric oxidants control the lifetime of many chemical species within the atmosphere and their abundances are expected to change with climate. The relative abundance of ozone and HOx (= OH + HO2 + RO2) species controls the Δ17O-excess of nitrate, allowing nitrate deposited in ice cores to be used as a proxy for historical oxidant abundances. New measurements from the West Antarctic Ice Sheet (WAIS) Divide ice core are presented and compared to previous results from a Greenland ice core. The observations cover the glacial-interglacial difference and several rapid climate change events (Dansgaard-Oeschger events) during the last glacial period. Oxidant abundances show clear shifts with climate, and we explore potential reasons for oxidant abundance shifts including changes in tropospheric ozone formation and changes in stratosphere-troposphere exchange.
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