During the last decade Antarctic ice sheet accumulation patterns exhibited large regional differences. While the total ice-sheet mass of Antarctica declined, East Antarctica experienced increases in ice mass. During 2009 and 2011, this increase was caused by only a handful of intense precipitation events. In this study, we investigate such an episodic accumulation event, thereby exploring linkages between oceanic evaporation in subtropical regions and Antarctic ice-sheet accumulation.

We use both Eulerian and Lagrangian analysis to demonstrate that the moisture transport was facilitated by several cyclones of different scales. Long-range moisture transport towards East-Antarctica occurred in a coherent air-stream. This moist-conveyor belt was initially embedded in the warm-sector of a synoptic scale cyclone, with slantwise, isentropic ascent contributing to the poleward moisture transport. As this synoptic cyclone decays, a rapidly developing secondary cyclone assists the moisture transport by providing strong moisture-flux-convergence. Oceanic evaporation along the filamentary structured, anomalous moisture transport area was virtually absent, in addition the atmosphere was cooled by surface sensible heat fluxes. Both effects contributed to the decoupling of the moist-conveyor-belt from the underlying ocean. Lagrangian trajectory-analysis of the moisture transport corroborate these findings, in addition it enabled identification of the moisture source region for extreme precipitation over East Antarctica. The moisture-source region was located around 40S and exhibited anomalously high sea-surface temperatures.