[A-CG47] 海洋と大気の波動・渦・循環の力学

[ACG47-P07] Generation of the Equatorial Deep Jets in the Pacific Ocean

*寺田 雄亮¹、升本 順夫^1,2 (1.東京大学理学系研究科、2.海洋研究開発機構)

The Equatorial Deep Jets (EDJs) are the equatorially trapped, vertically alternating eastward and westward currents observed in all three major basins. The EDJs exhibit inter-annual or decadal variability depending on the basin with a downward phase propagation. Although there are several attempts to simulate the EDJs and to explore their generation mechanisms using numerical models, the EDJs are either not reproduced or are incompletely represented in most ocean general circulation models (OGCMs). Recently, Argo observations have revealed the existence of 30-day period Yanai waves (Mixed-Rossby-Gravity waves) at 1000m in the eastern Pacific Ocean, which is a possible energy source of the EDJs. Here, we conduct numerical simulations to reproduce the EDJs in the Pacific Ocean and investigate the contribution of the Yanai waves to the generation of the EDJs. The results show that the Yanai waves in the eastern basin primarily provide energy to the EDJs through the convergence of the zonal momentum. Furthermore, sensitivity experiments with different bottom friction suggest that the location of the major energy sink of the EDJs determines the direction of the vertical phase propagation of the EDJs. The sensitivity of the EDJs’ vertical scale to the vertical viscosity is also discussed in this presentation.