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第360回 大気海洋物理学・気候力学セミナー のおしらせ

日　時：4月21日 (木) 9:30 - 11:00
Date ：Thu., 21 Apr 9:30 - 11:00
場所：環境科学院 D201室
Place ：Env. Sci. Bldg. D201

発表者：Gemma K. O'Connor（Department of Earth and Space Sciences, the University of Washington/ PhD candidate）
Speaker：Gemma K. O'Connor (Department of Earth and Space Sciences, the University of Washington/ PhD candidate)
Title：20th century atmospheric circulation around West Antarctica and implications for Antarctic ice loss ­

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20th century atmospheric circulation around West Antarctica and implications for Antarctic ice loss
Gemma K. O'Connor（Department of Earth and Space Sciences, the University of Washington/ PhD candidate）
発表要旨：

        Outlet glaciers in West Antarctica are rapidly retreating, which could
        lead to the collapse of the West Antarctic Ice Sheet and contribute to
        over 3m of sea level rise. The most rapid retreat is occurring in the
        Amundsen Sea sector, where glaciers are melting via exposure to warm
        ocean water called Circumpolar Deep Water (CDW). Local atmospheric
        circulation controls the transport of CDW, so there is a hypothesis that
        a change in atmospheric circulation occurred, enhancing the transport of
        CDW toward the glaciers, triggering the start of glacier retreat.
        Climate data in this region start only in 1979, making it difficult to
        evaluate whether such a change occurred. Thus, it remains unknown why
        ice loss is occurring in West Antarctica. I extend the climate record by
        combining proxy data (e.g., ice core and coral records) with climate
        model simulations to reconstruct atmospheric circulation around
        Antarctica since 1900. The reconstructions prove to be reliable compared
        to available instrumental data, demonstrating that this approach is
        useful. The reconstructions show evidence for a very strong westerly
        wind event around 1940, which is consistent with the hypothesized timing
        of the start of the glacier retreat. The 1940 event is therefore a
        candidate atmospheric anomaly that may have initiated the retreat. It
        remains unknown how such large atmospheric events affect the transport
        of warm ocean water in the Amundsen Sea (and therefore glacier melt), so
        I use numerical ocean modeling to simulate the ocean response to large
        wind events. In this seminar, I will present the reconstructions of
        atmospheric circulation around Antarctica, the changes in winds that the
        reconstructions reveal, and preliminary results from ocean simulations
        that I am working on during my visit at ILTS.  
        
        
        Biography
         Gemma O’Connor is a PhD candidate in the department of Earth and Space
        Sciences at the University of Washington in Seattle, Washington. She
        received a bachelor’s degree in Industrial and Systems Engineering at
        the Georgia Institute of Technology in 2017, where she also conducted
        research on the El Niño-Southern Oscillation using coral proxies. She
        now works in Dr. Eric Steig’s research group, where her research focus
        is on past atmospheric and oceanic circulation around West Antarctica.
        She is a visiting researcher working with Dr. Yoshihiro Nakayama’s
        research group at ILTS until July.
    

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