Observed three dimensional distributions of enhanced turbulence near the Luzon Strait

Jianfeng Wang,Qiang Ren,Fei Yu,Feng Nan,Tongtong Zheng,Zifei Chen

doi:10.1038/s41598-021-94223-3

Abstract

Ocean turbulence can impact the transfer of heat, nutrients, momentum and sea level rise, which are crucially important to climate systems. The Luzon Strait, one of the mixing hotspots, is important for water exchange between the northeastern South China Sea and West Pacific. Here, for the first time, we carry out full-depth direct microstructure measurements surrounding the Luzon Strait to clarify the three-dimensional distributions of turbulence. We demonstrate that the turbulent kinetic energy dissipation rates in the upper and middle layers of the northeastern South China Sea are on the same order of magnitude as those in the West Pacific. The dissipation rates are only bottom enhanced near the rough topography of the South China Sea slope and Luzon Strait which is one order of magnitude larger than those at smooth area. The relevant bottom diapycnal diffusivity in the South China Sea is elevated in the West Pacific by a factor of three, instead of by two orders of magnitude as overestimated by indirect parameterization. These results may appear surprising in light of previous studies but are in fact consistent with predictions from internal wave-topography interaction theory.

Highlights

Ocean turbulence can impact the transfer of heat, nutrients, momentum and sea level rise, which are crucially important to climate systems
Turbulent mixing in the Luzon Strait (LS) drives water exchange between the northeastern South China Sea (NSCS) and the West Pacific (WP), which is important for NSCS circulation and heat and salt budgets[12]
Field observations were performed at 24 stations from May 29 to June 24, 2018, and from July 21 to August 5, 2019, in the NSCS and WP (Table 1), which covered a wide range of bathymetric and oceanographic conditions (Fig. 1)

Summary

Introduction

Ocean turbulence can impact the transfer of heat, nutrients, momentum and sea level rise, which are crucially important to climate systems. We demonstrate that the turbulent kinetic energy dissipation rates in the upper and middle layers of the northeastern South China Sea are on the same order of magnitude as those in the West Pacific. The relevant bottom diapycnal diffusivity in the South China Sea is elevated in the West Pacific by a factor of three, instead of by two orders of magnitude as overestimated by indirect parameterization. These results may appear surprising in light of previous studies but are consistent with predictions from internal wave-topography interaction theory. Numerical predictions of energy budgets cannot be tested without direct microstructure

Objectives

Methods

Results

Conclusion