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Laboratory experiments on diffusive convection layer thickness and its oceanographic implications
Author(s) -
Guo ShuangXi,
Zhou ShengQi,
Qu Ling,
Lu YuanZheng
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2016jc012172
Subject(s) - buoyancy , convection , convective boundary layer , stratification (seeds) , boundary layer , thermal diffusivity , thermal , mechanics , thermal stratification , materials science , convective heat transfer , layer (electronics) , mixed layer , geology , flux (metallurgy) , thermodynamics , meteorology , planetary boundary layer , turbulence , physics , composite material , dormancy , seed dormancy , germination , botany , metallurgy , biology
Abstract We studied the thickness of diffusive convective layers that form when a linearly stratified fluid is subjected to heating from below in the laboratory. The thickness of the bottom convecting layer is much larger than subsequent layers. These thicknesses are systematically identified and used to examine the available convecting layer thickness parameterizations, which are consisted of the measured heat flux F (or thermal buoyancy flux q T ), initial stratification N , density ratio R ρ , thermal diffusivity κ T , etc. Parameterization with an intrinsic length scale(q T 3κ TN 8) 1 / 4is shown to be superior. Including the present laboratory convecting layer thicknesses and those observed in oceans and lakes, where layer thickness ranges from 0.01 to 1000 m, the parameterization is updated as H = C( R ρ − 1 ) 2(q T 3κ TN 8) 1 / 4, where C = 38.3 for the bottom convective layer and 10.8 for the subsequent layers. Different prefactors are proposed to be attributed to different convective instabilities induced by different boundary conditions.