BOOK REVIEW | Chemical Oceanography (Third Edition)

Dynamics of Atmospheres and Oceans, 1978

2013

Ocean Dynamics, 2015

2005

Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution

Annual Review of Fluid Mechanics, 2004

Key Words ocean circulation, ocean mixing, ocean circulation energy s Abstract The coexistence in the deep ocean of a finite, stable stratification, a strong meridional overturning circulation, and mesoscale eddies raises complex questions concerning the circulation energetics. In particular, small-scale mixing processes are necessary to resupply the potential energy removed in the interior by the overturning and eddy-generating process. A number of lines of evidence, none complete, suggest that the oceanic general circulation, far from being a heat engine, is almost wholly governed by the forcing of the wind field and secondarily by deep water tides. In detail however, the budget of mechanical energy input into the ocean is poorly constrained. The now inescapable conclusion that over most of the ocean significant "vertical" mixing is confined to topographically complex boundary areas implies a potentially radically different interior circulation than is possible with uniform mixing. Whether ocean circulation models, either simple box or full numerical ones, neither explicitly accounting for the energy input into the system nor providing for spatial variability in the mixing, have any physical relevance under changed climate conditions is at issue.

Reviews of Geophysics, 1979

Progress in measuring• interpreting, and understanding oceanic internal gravity waves and fine and microstructure is reviewed; we emphasize the quadrennium 1975-1978. The context is how these subjects contribute to oceanic mixing. The overlap between the areas is examined, as is the relevance of the subjects to other aspects of oceanography.

Bulletin of the American Meteorological Society, 2020

Journal of Geophysical Research, 2012

Horizontal mixing and the distribution of coherent structures in the global ocean 1 are analyzed using Finite-Size Lyapunov Exponents (FSLE), computed for the sur-2 face velocity field derived from the Ocean general circulation model For the Earth 3 Simulator (OFES). FSLEs measure horizontal stirring and dispersion; additionally, 4 the transport barriers which organize the oceanic flow can roughly be identified 5 with the ridges of the FSLE field. We have performed a detailed statistical study, 6 particularizing for the behaviour of the two hemispheres and different ocean basins. 7 The computed Probability Distributions Functions (PDFs) of FSLE are broad and 8 asymmetric. Horizontal mixing is generally more active in the northern hemisphere 9 than in the southern one. Nevertheless the Southern Ocean is the most active 10 ocean, and the Pacific the less active one. A striking result is that the main cur-11 rents can be classified in two "activity classes": Western Boundary Currents, which 12 have broad PDFs with large FSLE values, and Eastern Boundary Currents with 13 narrower ranges and lower FSLE values. Both classes are also found when we corre-14 late FSLE fields with Eddy Kinetic Energy (EKE) and vorticity (ω), with particular 15 dispersion relations. These relations characterize the dynamics of different ocean ar-16 eas, which would influence the presence and evolution of biological markers, among 17 other variables.

Declaration I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgment is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged. i Abstract The relationship between the general circulation of the ocean and, alongisopycnal and vertical mixing is explored. Firstly, advection down isopycnal tracer gradients is related to mixing in specific regions of the ocean. Secondly, a general inverse method is developed for estimating both mixing and the general circulation. Two examples of down gradient advection are explored. Firstly the region of Mediterranean outflow in the North Atlantic. Given a known transport of warm salty water out of the Mediterranean Sea and the mean hydrography of the eastern North Atlantic, the vertical structure of the along-isopycnal mixing coefficient, K, and the vertical mixing coefficient, D, is revealed. Secondly, the Southern Ocean Meridional Overturning Circulation, SMOC, is investigated. There, relatively warm salty water is advected southward, along-isopycnals, toward fresher cooler surface waters. The strength and structure of the SMOC is related to K and D by considering advection down along-isopycnal gradients of temperature and potential vorticity. The ratio of K to D and their magnitudes are identified. A general tool is developed for estimating the ocean circulation and mixing; the tracer-contour inverse method. Integrating along contours of constant tracer on isopycnals, differences in a geostrophic streamfunction are related to advection and hence to mixing. This streamfunction is related in the vertical, via an analogous form of the depth integrated thermal wind equation. The tracer-contour inverse method combines aspects of the box, beta spiral and Bernoulli methods. The tracer-contour inverse method is validated against the output of a layered model and against in-situ observations from the eastern North Atlantic. The method accurately reproduces the observed mixing rates and reveals their vertical structure. ii iii Bates for fruitful discussions at UNSW. Although I have not subjected them to reading this thesis, except this section, I would like to thank my girlfriend Ella and my parents Paul and Katrina, for their loving support over the years. iv