Modelling Large Ocean to Atmosphere Heat Flux events in the Amundsen Sea Embayment, West Antarctica

The glaciers of the Amundsen Sea Embayment are amongst the most rapidly retreating in Antarctica. Relatively warm circumpolar deep water is transported on to the continental shelf and leads to basal melting of floating ice shelves. Recent research has shown the importance of local processes such as sea ice formation in determining the ocean heat content (and subsequent glacial melt) in the vicinity of Pine Island and Thwaites glaciers. Cold air outbreaks and their associated large heat fluxes from the ocean to the atmosphere are important for the formation and transport of sea ice, for example, strong easterly winds of 15-20 ms^-1 can sporadically generate wintertime coastal polynyas in the Eastern Amundsen Sea Embayment. Here we examine a recent case study of a high heat flux and coastal polynya event from October 2011, using high horizontal grid resolution (2.2km) numerical weather prediction simulations with the Met Office Unified Model. We find maximum turbulent heat fluxes of up to 1100 Wm^-2 close to the coastline within Pine Island Bay with similar values being sustained for a period of around 96 hours. For this case study we compare the magnitude of the heat fluxes given by the high resolution model to both those from a coarser version of the model (25km grid size) and global reanalysis products. We investigate systematic differences in both the magnitude and spatial extent of the surface fluxes over the Pine Island Bay region and consider the importance of these for ocean modelling studies.