|Criscitiello, A.S., Das, S.B., Karnauskas, K., Evans, M., Frey, K., Joughin, I., Steig, E., McConnell, J., Tropical Pacific influence on source and transport of marine aerosols to West Antarctica, In revision (2013)|
Recent warming in continental West Antarctica has been shown to be linked to sea-surface temperature (SST) changes in the tropical Pacific over the past 30 years. Anomalous SSTs in the tropical Pacific have generated an atmospheric Rossby wave response that influences atmospheric circulation over the Amundsen Sea, causing increased advection of warm air to the Antarctic continent. Here we show that by affecting atmospheric circulation at high southern latitudes, coupled ocean-atmosphere variability in the tropical Pacific also influences the transport of marine-derived aerosols to the coastal ice sheet. We use ECMWF and NOAA atmospheric reanalysis data to investigate the link between sea-ice modulated species (namely methanesulfonic acid (MSA) and sea salts (Na+ and Cl-)) from a suite of coastal firn cores from the Amundsen Coast of West Antarctica and large-scale atmospheric changes in the tropical Pacific. Our results indicate significant correlations between sea-ice proxy concentrations (MSA and sea salts) in the firn cores and SSTs and SLPs in the tropical Pacific. The alternating cyclones and anticyclones at the surface and throughout the atmospheric column suggest a barotropic response of the atmosphere connecting the western tropical Pacific with the Antarctic Peninsula. La Niña-like conditions (anomalous cooling in the eastern tropical Pacific) generate an atmospheric Rossby wave response that influences atmospheric circulation over the Antarctic Peninsula, resulting in cyclonic winds over the Antarctic Peninsula and a reduction in onshore wind velocities at Pine Island Bay. Our results indicate that the tropical Pacific exerts a primary control on the source and transport efficiency of MSA and sea salts to the Amundsen Coast.