Characterization of Mixing at the Edge of a Kuroshio Intrusion into the South China Sea: Analysis of Thermal Variance Diffusivity Measurements
Journal
Journal of Physical Oceanography
Journal Volume
54
Journal Issue
5
Start Page
1121
End Page
1142
ISSN
0022-3670
1520-0485
Date Issued
2024-05
Author(s)
Sanchez-Rios, Alejandra
Shearman, R. Kipp
Lee, Craig M.
Simmons, Harper L.
Laurent, Louis St.
Lucas, Andrew J.
Ijichi, Takashi
Abstract
The Kuroshio occasionally carries warm and salty North Pacific Water into fresher waters of the South China Sea, forming a front with a complex temperature–salinity (T–S) structure to the west of the Luzon Strait. In this study, we examine the T–S interleavings formed by alternating layers of North Pacific Water with South China Sea Water in a front formed during the winter monsoon season of 2014. Using observations from a glider array following a free-floating wave-powered vertical profiling float to calculate the fine-scale parameters Turner angle, Tu, and Richardson num-ber, Ri, we identified areas favorable to double-diffusion convection and shear instability observed in a T–S interleaving. We evaluated the contribution of double-diffusion convection and shear instabilities to the thermal variance diffusivity, x, using microstructure data and compared it with previous parameterization schemes based on fine-scale properties. We dis-cover that turbulent mixing is not accurately parameterized when both Tu and Ri are within critical ranges (Tu. 60; Ri,1=4). In particular, x associated with salt finger processes was an order of magnitude higher (6.7 3 1027 K2 s21) than in regions where only velocity shear was likely to drive mixing (8.7 3 1028 K2 s21).
Subjects
Asia
Fronts
Mixing
Oceanic profilers
Ship observations
Small-scale processes
SDGs
Publisher
American Meteorological Society
Type
journal article