Presentation Information
[AOS25-P03]Deep water properties observed around the Yap-Mariana Junction in the winter of 2021 and summer of 2018
*Masatoshi Miyamoto1, Kodai Yamada1, Mitsuho Oe1, Yasutaka Goto1, Ichiro Yasuda3, Daigo Yanagimoto2, Daisuke Sasano1 (1.JMA, 2.AORI, UTokyo, 3.JAMSTEC)
Keywords:
Yap-Mariana Junction,Lower Circumpolar Deep Water,Deep Circulation
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.