DOI: 10.1002/2017JC013242
Scopus记录号: 2-s2.0-85042219471
论文题名: Quantifying Diapycnal Mixing in an Energetic Ocean
作者: Ivey G.N. ; Bluteau C.E. ; Jones N.L.
刊名: Journal of Geophysical Research: Oceans
ISSN: 21699275
出版年: 2018
卷: 123, 期: 1 起始页码: 346
结束页码: 357
语种: 英语
英文关键词: Indian Ocean
Scopus关键词: diffusivity
; instrumentation
; laboratory method
; microstructure
; mooring system
; prediction
; quantitative analysis
; Richardson number
; shear flow
; time series
; tracer
; turbulence
; Indian Ocean
英文摘要: Turbulent diapycnal mixing controls global circulation and the distribution of tracers in the ocean. For turbulence in stratified shear flows, we introduce a new turbulent length scale Lρ dependent on χ. We show the flux Richardson number Rif is determined by the dimensionless ratio of three length scales: the Ozmidov scale LO, the Corrsin shear scale LS, and Lρ. This new model predicts that Rif varies from 0 to 0.5, which we test primarily against energetic field observations collected in 100 m of water on the Australian North West Shelf (NWS), in addition to laboratory observations. The field observations consisted of turbulence microstructure vertical profiles taken near moored temperature and velocity turbulence time series. Irrespective of the value of the gradient Richardson number Ri, both instruments yielded a median Rif=0.17, while the observed Rif ranged from 0.01 to 0.50, in agreement with the predicted range of Rif. Using a Prandtl mixing length model, we show that diapycnal mixing Kρ can be predicted from Lρ and the background vertical shear S. Using field and laboratory observations, we show that Lρ=0.3LE where LE is the Ellison length scale. The diapycnal diffusivity can thus be calculated from Kρ=0.09LES2. This prediction agrees very well with the diapycnal mixing estimates obtained from our moored turbulence instruments for observed diffusivities as large as 10-1 m2s−1. Moorings with relatively low sampling rates can thus provide long time series estimates of diapycnal mixing rates, significantly increasing the number of diapycnal mixing estimates in the ocean. © 2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114747
Appears in Collections: 气候减缓与适应
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作者单位: Oceans Graduate School and the Oceans Institute, University of Western Australia, Crawley, WA, Australia; Now at Institut des Sciences de la Mer, Universite du Quebec a Rimouski, Rimouski, QC, Canada
Recommended Citation:
Ivey G.N.,Bluteau C.E.,Jones N.L.. Quantifying Diapycnal Mixing in an Energetic Ocean[J]. Journal of Geophysical Research: Oceans,2018-01-01,123(1)