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-OS 海洋科学・海洋環境

[A-OS11] What we have learned about ocean mixing in the last decade

2018年5月21日(月) 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:日比谷 紀之(東京大学大学院理学系研究科地球惑星科学専攻)、Louis St Laurent (Woods Hole Oceanographic Institution)、Ren-Chieh Lien(None、共同)、Robin Ann Robertson (Xiamen University Malaysia)

[AOS11-P09] Observation of Internal Waves in Luzon Strait by the repeated XBT surveys

*酒井 秋絵1千手 智晴2堤 英輔2松野 健2郭 新宇3安田 一郎4 (1.九州大学大学院総合理工学府大気海洋環境システム学専攻、2.九州大学応用力学研究所、3.愛媛大学沿岸環境科学研究センター、4.東京大学大気海洋研究所)

キーワード:ルソン海峡、内部波

Luzon strait is known to create large amplitude internal waves. Many observations have been made in the strait (ex, Rainville et al. 2013), but few studies measured both temporal and spatial variations simultaneously. To reveal the generation and propagation processes of internal waves in the strait, we carried out repeated observations around a ridge in Luzon Strait with XBT, shipboard and moored ADCPs by R/V Hakuho-Maru in November 2017.



Since Luzon strait has two meridional ridges, we set an observation line along 21° N from 121° 30’ E to 122° 10’ E. Along the observation line, we casted XBT or XCTD at every 2.5 min in longitude, except for the interval from 121° 50’ E to 122° 00’ E, near the ridge, where every 1 min casts were made. Horizontal velocities down to about 500 m were measured with the shipboard ADCP set at the sampling interval and bin size of 8 s and 5 m, respectively. The series of observations were repeated 5 times during the period of November 22-27, and totally 6 cross sections were given. In addition to the repeat observations, we moored an ADCP at 20° 59.892' N 121° 45.136' E, west of the ridge, during the period of November 22-28, at the sampling intervals and bin size of 1 min and 8 m, respectively.



We here report only the results of the temperature observations. The thermocline represented by the 23 °C isotherm was temporary undulated in the upstream and downstream regions of the ridge. The comparison with flows from the mooring ADCP observation indicates a dominancy of the diurnal tide in this region. When the tidal current was weak, there were prominently tilted isotherms around the ridge. In some sections, wavy structures of isotherms, which have wavelength of about 10 km and high vertical mode, were recognized near the ridge. We observed temperature overturns (>0.05 °C) in the upstream region in the ridge in a section during strong eastward tidal current, which suggests generation of strong turbulent mixing.