Ocean Modelling and Fluids Group

We mostly study fluid dynamical processes in the context of the ocean, principally via computational methods. While the motivating context is on global/regional settings and we touch on climate/biogeochemistry/ecology/modelling applications, the focus is on the physical processes. On this site you can find information about our research projects (which also includes some non-ocean things we do), and the members making it happen.

Our research activities are funded by the RGC. We are also partly affiliated with the CORE program. Those interested in joining the group as a student/staff are generally welcome to contact Julian Mak, no guarantees we have openings though (we are essentially fully committed in terms of time and money at this present time). If you are looking for short projects (e.g. UG or MSc students, doesn't have to be within ocean science department itself), then please see blurb at this link.

News

Fei Er has been awarded the Anita Conti Fellowship scheme managed by the Consulate General of France in Hong Kong and Macau. She will be spending September to December 2023 as a visitor at the MEOM group at IGE Grenoble, working on something machine learning related.

Yongsu has been accepted to attend the Physics of the Ocean summer school at Bad Honnef, Germany for the 1st week of July.

Julian, Bobo and Fei Er attended the EGU General Assembly 2023 in Vienna, Austria in person, giving two talks and a poster. Convenient that Bobo's paper got accepted and had an early online release the day or two before the talk! (abstracts: Julian , Fei Er, Bobo.)

Yongqi defended her MPhil with the thesis title "Effect of Eddy Parameterization in Models with Continental Slopes".

Yongsu is on a six month visit to the CRIOS group at University of Texas at Austin, to work primarily with Patrick Heimbach and An Nguyen on utilising the ECCO machinery to carry out parameter inference calculations, and to set up regional state estimates.

Recent misc. outputs

On the choice of training data for machine learning of geostrophic mesoscale turbulence

F. E. Yan, J. Mak & Y. Wang [preprint]

Scale-awareness in an eddy energy constrained mesoscale eddy parameterization

J. Mak, J. R. Maddison, D. P. Marshall, X. Ruan, Y. Wang & L. Yeow [preprint]
J. Adv. Model. Earth. Syst.

Global estimation of the eddy kinetic energy dissipation from a diagnostic energy balance

R. Torres, R. Waldman, J. Mak & R. Séférian [doi]
Geophys. Res. Lett., 50, 2023GL104688

Combined physical and biogeochemical assessment of mesoscale eddy parameterisations in ocean models: eddy induced advection at non-eddying resolutions

X. Ruan, D. Couespel, M. Lévy, J. Li, J. Mak & Y. Wang [doi]
Ocean Modell., 183, 102204

Scalings for eddy buoyancy fluxes across prograde shelf/slope fronts

H. Wei, Y. Wang, A. L. Stewart & J. Mak [doi]
J. Adv. Model. Earth. Syst., 14(12), e2022MS003229

On constraining the mesoscale eddy energy dissipation time-scale

J. Mak, A. Avdis, T. W. David, H. S. Lee, Y. Na, Y. Wang & F. E. Yan [doi]
J. Adv. Model. Earth. Syst., 14(11), e2022MS003223

Acute sensitivity of global ocean circulation and heat content to eddy energy dissipation time-scale

J. Mak, D. P. Marshall, G. Madec & J. R. Maddison (2022) [doi]
Geophys. Res. Lett., 49(8), e2021GL097259

Animation of the Cahn-Hilliard equation with advection by a 2d Taylor-Green vortex flow at different strengths (courtesy of Haruki Saegusa, HKUST UG student).

Research Areas

Eddy parameterisation

One of the focus of the group is on mesoscale eddy parameterisation arising from baroclinic turbulence, particularly on the energetically constrained parameterisation GEMOETRIC. Research activities include evaluating the impact on the modelled ocean circulation, on constraining the unknown parameters/processes associated with eddy energetics, and on maintaining/developing/implementing the relevant codes in global circulation models.

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Inverse methods / state estimates

We deploy and develop code/models for tackling optimisation, inference and/or data assimilation problems in the ocean context. Current activities including constraining uncertain parameters associated with eddy energy constrained parameterisations, inference of uncertain physical processes in the South China Sea, employing both the Firedrake and MITgcm ECCO framework. Outlooks include uncertainty quantification and biogeochemical applications.

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Chaotic / turbulent stirring

Stirring (to highlight the central role played by advection) of tracers is intimately linked to eddy parameterisations, as well as having implications for modelling biogeochemistry, ecology and pollutant dispersion. We are particularly interested in the Lagrangian point of view for dispersion, in quantifying dispersion via methods in dynamical systems and/or more recent Bayesian methods, and the associated computational methods.

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Theoretical fluid dynamics (mostly GFD, some MHD)

A focus we have is on baroclinic lifecycles, baroclinic turbulence, wave/eddy-mean interaction and shear flow instabilities to complement the modelling work on eddy parameterisation. Current work involves employing optimisation principles in relation to baroclinic equilibration, baroclinic instabilities under the GEOMETRIC framework, as well as symmetry breaking in waves and instabilities.

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Current team

Mithrandir

Supreme lab manager

Webpage

A manifestation of the fluid state.

Julian Mak

Assistant Professor + code monkey

The group's code-fixer. See personal website for proper content.

Favourite fish: Ducks

Han Seul Lee

PhD student (since Sep 2020; internship at WMO Feb 2022 to Jan 2023)

Han Seul is currently researching the South China Sea circulation, using a finite element method that utilises Firedrake. Her fascination is with simple models, and the degree to which they do (and do not) reflect the real world. She received her MPhys degree from the University of Oxford, where she studied the Antarctic Circumpolar Current using an eddy-parameterizing model, looking at different parameterization schemes.

Ruan Xi (阮曦, Bobo)

MSc student (Jan - Jun 2020), PhD student (since Sep 2020)

Bobo's interest is in biophysical interactions in the ocean. She obtained a MSc degree in Environmental Health and Safety from HKUST. Before that, she gained experiences in biological science from Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences.

Yongsu Na

PhD student (since Sep 2020; visitor at the CRIOS group Jul to Dec 2022)

Webpage

Yongsu's main interest is a clear understanding of the natural phenomena associated with the ocean. He received his BSc and MEng from Korea University. He worked with Prof. Sangyoung Son on storm surge prediction using Delft3D and tropical cyclone prediction using echo state networks. He is currently working on the ocean mesoscale eddy parameterization using inverse methods and MITgcm. Along with his research, he enjoys playing sports (football, swimming, gym training) and skateboarding.

Yan Fei Er (嚴菲兒)

PhD student (since Feb 2021; Anita Conti fellowship to the MEOM group Sep to Dec 2023)

Fei Er's research interest is on the applications of machine learning methods to understanding oceanic mesoscale eddies. Fei Er obtained a MSc degree in Environmental fluid mechanics from the University of Grenoble Alpes, and another in Physical oceanography from the University of Bretagne Occidentale, France. Hobbies include swimming and hiking, undertaking a long-distance trail at least once a year.

Dan Bartley

Research Assistant (Jan 2022 - Jul 2022), MPhil student (since Sep 2022)

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Dan’s research interest lies in the physical interactions between natural environments and engineering interventions. He obtained a MEng degree in Civil Engineering from Imperial College London and has research experience in sediment transport, wetland management and artificial reefs. After work, Dan’s hobbies include hiking, video games and making music.

Kayla Lee Cho Kwan (李楚筠)

MPhil student (since Sep 2022; with Wang Yan)

Kayla's research interest is in tracing the transport pattern of ocean pollutants with Lagrangian techniques. She obtained her BSc in Environmental Science from HKUST.

Floriane Océane Sudre

Regular visitor (since Jul 2022)

Webpage

Floriane is currently a PhD student at the Mediterranean Institute of Oceanography in Marseille and was previously a research assistant in HKUST. Her research interest is at the interface between physical ocean processes and environmental issues, such as marine pollution and impacts on ecology. She holds a MSc in Engineering from France, and a MSc in Environmental Science, specializing in Climate Physics, from the University of Copenhagen. For her Master's thesis she studied the impact of lateral and bottom frictions on the Swedish Gullmars fjord under Prof. Markus Jochum supervision. Aside from ocean research, she loves running in the jungle, swimming in the sea, taking care of her garden and eating fresh figs.