Japan Geoscience Union Meeting 2018

Presentation information

[EE] Poster

A (Atmospheric and Hydrospheric Sciences) » A-OS Ocean Sciences & Ocean Environment

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

Mon. May 21, 2018 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Toshiyuki Hibiya(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Louis St Laurent (Woods Hole Oceanographic Institution), Ren-Chieh Lien(None, 共同), Robin Ann Robertson (China-ASEAN College of Marine Science Xiamen University Malaysia)

[AOS11-P02] Spatial distribution of turbulent mixing in the central Pacific inferred from Argo float data

*Cheng Lingqiao1 (1.Shanghai Ocean University)

Keywords:Turbulent mixing, Mean latitudinal variation, The fine-scale parameterization, Argo float data

A long-term mean turbulent mixing in the depth range of 200-1000 m produced by breaking of internal waves across the middle and low latitudes (40oS-40oN) of Pacific between 160oW and 140oW is examined by applying the fine-scale parameterization depending on strain variance to 8-year (2005-2012) Argo float data. The adequacy of Argo float data was validated by comparing the estimated turbulent dissipation rate (ε) with those from World Ocean Circulation Experiment (WOCE) data. It is found that although some underestimations may exist to estimate the exact intensity of turbulent mixing below 350 m, good correlations between εargo and εWOCE indicate the property of Argo data for investigation of spatial variation. Results show that elevated ε is obtained related to significant topographic regions, along the equator, and on the northern side of 20oN spanning to 24oN throughout the depth range. Two patterns of latitudinal variations of ε and the corresponding diffusivity (Kρ) for different depth ranges are confirmed: One is for 200-450 m with significant larger ε and Kρ, and the maximum values are obtained between 4oN-6oN, where eddy kinetic energy also reaches to its maximum; The other is for 350-1000 m with smaller ε and Kρ, and the maximum values are obtained near the equator, between 18oS-12oS and 20oN-22oN. Most elevated turbulent dissipation in the depth range of 350-1000 m relates to rough bottom roughness (correlation coefficient=0.63), excluding the equatorial area. In the temporal mean field, energy flux from surface wind stress to inertial motions is found not significant to account for the relatively intensified turbulent mixing in the upper layer.