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The climate of West Antarctica is strongly influenced by remote forcing from the tropical Pacific. For example, recent surface warming over West Antarctica reflects atmospheric circulation changes over the Amundsen Sea, driven by an atmospheric Rossby wave response to tropical sea surface temperature (SST) anomalies. Here, it is demonstrated that tropical Pacific SST anomalies also influence the source and transport of marine-derived aerosols to theWest Antarctic Ice Sheet. Using records from four firn cores collected along the Amundsen coast of West Antarctica, the relationship between sea ice-modulated chemical species and large-scale atmospheric variability in the tropical Pacific from 1979 to 2010 is investigated. Significant correlations are found between marine biogenic aerosols and sea salts, and SST and sea level pressure in the tropical Pacific. In particular, La Ni~na-like conditions generate an atmospheric Rossby wave response that influences atmospheric circulation over Pine IslandBay. Seasonal regression of atmospheric fields onmethanesulfonic acid (MSA) reveals a reduction in onshore wind velocities in summer at Pine Island Bay, consistent with enhanced katabatic flow, polynya opening, and coastal dimethyl sulfide production. Seasonal regression of atmospheric fields on chloride (C-) reveals an intensification in onshore wind velocities in winter, consistent with sea salt transport fromoffshore source regions. Both the source and transport of marine aerosols toWestAntarctica are found to bemodulated by similar atmospheric dynamics in response to remote forcing. Finally, the regional icecore array suggests that there is both a temporally and a spatially varying response to remote tropical forcing. © 2014 American Meteorological Society.

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Journal of Climate

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aerosol, atmospheric circulation, atmospheric forcing, atmospheric transport, marine atmosphere, Rossby wave, sea ice, sea level pressure, sea surface temperature, spatial variation, temperature anomaly, temporal variation, warming, wind velocity



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