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Contribution of Surface Thermal Forcing to Mixing in the Ocean
Author(s) -
Wang Fei,
Huang ShiDi,
Xia KeQing
Publication year - 2018
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc013578
Subject(s) - thermocline , mixing (physics) , forcing (mathematics) , thermal , flux (metallurgy) , zonal and meridional , mechanics , environmental science , geology , heat flux , thermohaline circulation , atmospheric sciences , climatology , meteorology , heat transfer , materials science , physics , quantum mechanics , metallurgy
A critical ingredient of the meridional overturning circulation (MOC) is vertical mixing, which causes dense waters in the deep sea to rise throughout the stratified interior to the upper ocean. Here, we report a laboratory study aimed at understanding the contributions from surface thermal forcing (STF) to this mixing process. Our study reveals that the ratio of the thermocline thickness to the fluid depth largely determines the mixing rate and the mixing efficiency in an overturning flow driven by STF. By applying this finding to a hypothetical MOC driven purely by STF, we obtain a mixing rate of O(10 − 6 m 2 / s ) and a corresponding meridional heat flux of O(10 − 2petawatt, PW), which are far smaller than the values found for real oceans. These results provide quantitative support for the notion that STF alone is not sufficient to drive the MOC, which essentially acts as a heat conveyor belt powered by other energy sources.