[M-IS05] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS05-14] Sea Ice Variations in Coastal Amundsen Sea Affected by Ice Shelf Meltwater

*KOFAN LU¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Amundsen Sea sea ice, Pine Island Glacier, Thwaites Glacier, ice shelf meltwater

Meltwater outflows from Pine Island Embayment become more important in changing the ocean circulations in the coastal Amundsen along with the elevated basal melt of ice shelves. Sea ice variations in Amundsen Sea is modified by a combination of thermodynamic and dynamic processes, while in coastal areas dynamical process determined by ocean circulations is more dominant. A melt rate-controlled model set is developed to study the changes of the surface hydrography and sea ice distributions when double the melt rate (~ +135 Gt/yr in total) of Pine Island and Thwaites Glaciers. The increasing meltwater outflows from Pine Island Embayment transport westward and flush the sea ice drift, leading to both lower sea ice concentration and thickness along the coast. Sea ice concentration drops ~2% in average inthe coastal areas and sea ice thickness reduces ~10 cm in maximum. Due to the declined albedo that follows the lower sea ice concentration, the sea surface temperature increases ~0.06°C in maximum. Although this surface warming occurs only in the upper layer (~100 m) and would not feedback to the ice shelf melt, the stored surface heat delays the sea ice formation and shorten freezing season. Changes of sea ice seasonal cycle by ice shelf meltwater are further investigated to evaluate the importance of thermodynamic and dynamic processes, which helps to assess the future sea ice trend under the climatological perturbations of surface heat budget in Amundsen Sea.