[A-CG36] 海洋と大気の波動・渦・循環の力学

[ACG36-08] Observations of internal waves in a Southern Ocean standing meander

*Ajitha Cyriac¹、Amelie Meyer^1,2、Helen Elizabeth Phillips^1,2,3,4、Nathan Bindoff^1,2,3,5 (1.Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia、2.Australian Research Council Centre of Excellence for Climate Extremes, University of Tasmania, Hobart, Australia、3.Australian Antarctic Program Partnership, University of Tasmania, Hobart, Australia、4.Australian Centre for Excellence in Antarctic Science, University of Tasmania, Hobart, Australia、5.CSIRO Marine and Atmospheric Research, Hobart, Australia)

Internal waves play an important role in the ocean kinetic energy budget by distributing significant amounts of heat and momentum through wave breaking. As they propagate away from their generation sites, internal waves exchange energy with each other (wave-wave interactions), or with the mean flow (wave-mean interactions) or dissipate as turbulent mixing. Thus, an understanding of the sources, subsequent propagation, and eventual dissipation of these waves is crucial in understanding the ocean's role in global climate. Here, we characterize the internal wave field in a standing meander near the Macquarie Ridge, a major topographic obstacle for the Antarctic Circumpolar Current (ACC), using field observations. Internal waves are identified as coherent features from more than 1400 profiles of temperature, salinity, and velocity of the upper ocean sampled by Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats. We identified a total of 112 features of which 68% are propagating upward and westward. The analysis suggests that the internal wave dynamics is highly influenced by the ACC through advection and wave-mean flow interactions leading to remote dissipation of the waves. The results show that the relative vorticity of the mean flow dominates the wave dynamics in this region. Finally, different possible generation mechanisms of the waves will be discussed.