Figure 7: Surface and mid-troposhere winds over Pliocene Antarctic landscape.

Modelled wind regimes over the warm Pliocene ice-sheet configuration (Fig. 2) during austral summer, DJF (December, January and February). (a) Near-surface winds are dominated by katabatic processes. Some Pliocene diatoms in the central TAMs may have been carried at relatively low altitudes from coastal exposures of a retreated Recovery Ice Stream near the Shackleton Range in the Weddell Sea sector or along the Ross Sea coast. Coastal storm events over the emerged Wilkes and Aurora basins would have provided the dominant mechanism for lifting a large volume of diatoms and other dust particles off exposed, snow-free surfaces to higher altitudes where they could be carried great distances. (b) Modelled winds at 500 hPa (∼5,000 m). Red arrow indicates likely dominant pathway for aeolian dust from Aurora Basin outcrops towards the TAMs. This configuration suggests that stratospheric rainout from a meteorite impact in the South Pacific Ocean would be towards the Ross Embayment, and thus ejecta would likely be more abundant along Marie Byrd Land and the Whitmore Mountains than the TAMs, though specific ejecta pathways have not investigated. Neither surface nor mid-altitude winds indicate significant pathways from the Ross Sea.