日本地球惑星科学連合2018年大会

講演情報

[EE] Eveningポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS02] 大規模な水蒸気場と組織化した雲システム

2018年5月22日(火) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:三浦 裕亮(国立大学法人 東京大学大学院 理学系研究科 地球惑星科学専攻)、濱田 篤(富山大学都市デザイン学部)、横井 覚(海洋研究開発機構、共同)、佐藤 正樹(東京大学大気海洋研究所)

[AAS02-P03] Dynamical mechanisms of anomalous moisture transport towards East Antarctica

*Annick Terpstra2,1Harald Sodemann1Irina Gorodetskaya2 (1.Geophysical Institute, University of Bergen, Norway and Bjerknes Centre for Climate Research, Bergen, Norway、2.Center for Environment and Marine Studies, University of Aveiro, Portugal)

キーワード:moisture transport, East-Antactica, evaporation-precipitation linkages

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 the atmospheric linkages between oceanic evaporation in subtropical regions and Antarctic ice-sheet accumulation. As Antarctic ice-sheet accumulation, and thus sea-level change, is contingent on episodic snow events, understanding the underlying dynamical mechanisms is instrumental for assessing global sea-level changes.

We use both Eulerian and Lagrangian analysis to demonstrate that moisture transport was facilitated by several cyclones of different scales. Moisture transport towards East-Antarctica occurred in coherent air-streams, manifested initially as intense low-level jets embedded in the warm sector of the cyclone(s), followed by a transition to slantwise (pseudo-isentropic) ascent before reaching the continent. Water vapor loading of this moist-conveyor-belt was driven by low-level convergence in the warm sector along the advancing cold-front, whereas the slantwise ascent phase of the moisture transport was characterized by moisture removal (precipitation). Oceanic evaporation along the filamentary structured, anomalous moisture transport area was virtually absent, indicative for long-range moisture transport during the event. In addition to the moisture transport mechanisms we identified moisture source regions associated with the event.