講演情報
[AOS25-P03]Deep water properties observed around the Yap-Mariana Junction in the winter of 2021 and summer of 2018
*宮本 雅俊1、山田 広大1、大江 光穂1、後藤 恭敬1、安田 一郎3、柳本 大吾2、笹野 大輔1 (1.気象庁、2.東大大気海洋研究所、3.海洋研究開発機構)
キーワード：
ヤップ・マリアナジャンクション、下部周極深層水、深層循環
To clarify the water transformation and volume transport of Lower Circumpolar Deep Water (LCDW) at the Yap-Mariana Junction (YMJ), where is the main gateway from the Yap and Mariana Trenches (YMTs) to the Parece Vela Basin (PVB), hydrographic observations were conducted in the winter of 2021 and summer of 2018. Vertical profiles of water properties were divided into two in the PVB and the YMTs at depths greater than ~ 4,000 m, associated with LCDW passing through a sill in the YMJ at 12.4°N 139.0°E. In the winter of 2021, LCDW entering the PVB was observed below a depth of 4,300 m (σ4 > 45.895 kg m-3, where σ4 is the potential density referenced to 4,000 dbar) at 13.0°N, 139.0°E, north of the sill, which was consistent with the northward flow observed by lowered acoustic Doppler current profilers. In the summer of 2018, LCDW with water characteristic of the PVB side was observed south of the sill at the YMTs side at depths of 3,900–4,200 m (45.875 < σ4 < 45.885 kg m-3) at 12.0°N, 139.0°E. The estimated volume transports passing through the YMJ were 0.9–2.4 Sv (1 Sv ≡ 106 m3 s-1) and 0.3–0.9 Sv in the winter of 2021 and summer of 2018, respectively, which were probably affected by seasonal variability around the YMJ as observed in past studies.