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

We are hosting colleagues from the AMSL group at Yonsei on Friday 2nd of October as part of a HKUST-Yonsei University seed grant; see here for rundown of activities.

Welcome to Luwei who is joining as a post-doc from ANU. Luwei will be working on the energetic coupling between lee wave parameterisations and the GEOMETRIC parameterisation in NEMO, somewhat based on the topic of her PhD thesis.

Welcome to Tim and Ryan. Tim is joining as a PhD student working broadly on machine learning related problems for turbulence. Ryan is joining as a MPhil student working on stochastic models for climate and large deviation theory (motivated in part by his interest in modelling financial markets).

Julian got the Outstanding Editor Award 2025 for EGU Ocean Sciences.

The project MOBIM (with French side PI Marina Lévy) was funded through the ANR/RGC Joint Research Scheme, on work relating to the influence of mesoscale eddy parameterisations and impact on ventilation of oxygen and carbon in the ocean, with a view to contribute towards the upcoming O/CMIP exercises.

Recent misc. outputs

Animation of surface current speed in the Spilhaus projection. Data from NEMO ORCA0083-N01 output available on JASMIN (raw data here; I did quite a bit of downsizing...) Visualised with Matplotlib and Cartopy.

An energetically and observationally constrained mesoscale parameterization for ocean climate models

R. Torres^, R. Waldman, G. Madec, C. de Lavergne, R. Séférian & J. Mak (2025) [doi]
J. Adv. Model. Earth Syst., 17(12), e2025MS005394

Negative sensitivity of Southern Ocean circumpolar transport to increased wind stress controlled by residual overturning

H. S. Lee, J. R. Maddison, J. Mak, D. P. Marshall & Y. Wang (2025) [doi]
Tellus A, 77(1), 199-220

Adjoint-based online learning of two-layer quasi-geostrophic baroclinic turbulence

F. E. Yan, H. Frezat, J. Le Sommer, J. Mak & K. Otness (2025) [doi]
J. Adv. Model. Earth Syst., 17(7), e2024MS004857

A two-dimensional model for eddy saturation and frictional control in the Southern Ocean

J. R. Maddison, D. P. Marshall, J. Mak & K. Maurer-Song (2025) [doi]
J. Adv. Model. Earth. Syst., 17(4), e2024MS004682

Edge-wave phase shifts versus normal-mode phase tilts in an Eady problem with a sloping boundary

J. Mak, N. Harnik, E. Heifetz, G. Kumar & E. Q. Y. Ong (2024) [doi]
Phys. Rev. Fluids, 9(8), 083905
(editor's highlight)

Animation of the some Lagrangian particles (labelled as rubber ducks) being dispersed in a time-periodic double gyre flow. Driver code by Dan Bartley.

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

X. Ruan, D. Couespel, M. Lévy, J. Li, J. Mak & Y. Wang (2024) [doi]
Ocean Modell., 190, 102396

Scale-awareness in an eddy energy constrained mesoscale eddy parameterization

J. Mak, J. R. Maddison, D. P. Marshall, X. Ruan, Y. Wang & L. Yeow (2023) [doi]
J. Adv. Model. Earth. Syst., 15(12), e2023MS003886

Research Areas

eddies

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

miffji

Mithrandir

Supreme lab manager

A manifestation of the fluid state.

julian

Julian Mak

Associate Professor + senior code monkey (since Jul 2025)
Assistant Professor + code monkey (Jul 2019 -- Jun 2025)
NOC associate (since Sep 2023)

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

Favourite fish: Ducks

Bobo

Ruan Xi (阮曦, Bobo)

Post-doc (since Jul 2025)
PhD student (Sep 2020 - May 2025)
Anita Conti fellowship to the LOCEAN group (Host: Marina Levy, Sep - Dec 2024)
MSc student (Jan - Jun 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.

jonathan

Lee Ho Ching (李皓澄, Jonathan)

PhD student (HKPFS awardee; since Feb 2024)

Jonathan has a keen interest in studying Earth Science related problems using computational methods. He obtained both BSc Geophysics and MSc Applied Computational Science and Engineering degree from Imperial College London, in which he gained experience in applying numerical modelling and machine learning to various aspects of Earth Science, including geophysical fluid dynamics. Currently, he is using Firedrake / Thetis for storm surge inversion and ocean-related optimisation problems.

virryna

Wu Yue (吳越, Virryna)

Post-doc (since Feb 2024)
Anita Conti Fellowship to LOPS IFREMER (Host: Camille Lique, Sep - Dec 2025)

Virryna's interest lies in understanding the ocean processes at high latitudes, including sea ice change, ocean circulations, air-sea interaction, and climate change. She holds a PhD from the University of East Anglia, where her research delved into the ocean response to Arctic sea ice retreat using coupled climate models in subpolar regions such as the Nordic Seas, Barents Sea, and Svalbard. Prior to that, she obtained a MRes degree in Ocean Sciences from the University of Southampton, with research experience in Arctic upper ocean circulation, particularly in the Beaufort Gyre. Outside of work, Virryna enjoys photography, cooking and baking.

fafa

Fa Fa (花花)

Assistant supreme lab manager

Another manifestation of the fluid state.

floriane

Floriane Océane Sudre

Post-doc (since Aug 2025)
Regular visitor (Jul 2022 - Feb 2024)
Research assistant (Mar 2020 - May 2021)

Floriane is a French physical oceanographer who completed her PhD in 2024, focusing on high-resolution ocean modeling and the dynamics of ocean fronts. After gaining experience in both academic research and data science consulting, she recently relocated to Hong Kong to join her husband and continue exploring her passion for the ocean’s physical processes, their influence on ecosystems, and the connections between coastal cities and marine environments. Outside of research, she enjoys reading, swimming and playing racket sports.

jiahui

Yin Jiahui (殷嘉慧)

MPhil student (since Sep 2025)

Jiahui is interested in applying mathematical and theoretical approaches to Earth science problems, particularly fluid dynamics in the ocean and other natural systems. She obtained BSc in Mathematics from The Chinese University of Hong Kong. She is currently researching transient instabilities in fluid systems relevant to the ocean.

samantha

Samantha Leung Wai Hang (梁慧姮)

MPhil student (since Sep 2025)

Samantha is currently pursuing an MPhil degree, focusing on steric sea level contributions in the Greater Bay and South China Sea region. She completed her undergraduate degree in Ocean Science and Technology from HKUST, where she developed a strong foundation in physical oceanography.

tim

Tim Du Tian Ju (都天炬)

PhD student (since Sep 2026)

Tim's research sits at the intersection of machine learning, physics-informed AI (SciML), and atmospheric/ocean dynamics, focusing on coastal surrogate modeling and spatiotemporal forecasting. He obtained a BSc in Environmental Science from HKUST and an MSc in Environmental Data Science and Machine Learning from Imperial College London, and has worked on AI-driven ESG risk monitoring. Through these experiences, he gained expertise applying data assimilation, remote sensing, and machine learning to Earth systems, including coastal wave dynamics and satellite-derived solar irradiance retrieval.

ryan

Ryan Chan Chun Ting (陳震梃)

MPhil student (since Sep 2026)

Here be tumbleweeds...

luwei

Yang Luwei (楊魯薇)

Post-doc (since Oct 2026)

Luwei's research focuses on understanding how small-scale ocean processes, particularly internal waves, influence large-scale ocean circulation. She has worked on lee waves generated by ocean currents flowing over rough topography, wind-generated internal waves, and internal tides. She uses a combination of theory, numerical modeling, and in situ and satellite observations to understand how these waves transfer energy across scales and how their effects can be better represented in global ocean and climate models. 

Dearly departed

HanSeul

Han Seul Lee
(Sep 19 - Sep 25)
PhD student
PDRA at Universite Catholique de Louvain

Yongsu

Yongsu Na
(Sep 20 - Aug 25)
PhD student
PDRA at OIST

Feier

Fei Er Yan
(Feb 21 - Mar 25)
PhD student
PDRA at Columbia University

dan

Dan Bartley
(Sep 22 - Aug 24)
MPhil student
PhD at Imperial College

huanhuan

Wang Huanhuan
(Sep 22 - Feb 23)
Post-doc
RA at HKU

gautam

Gautam Kumar
(Mar 21 - Sep 22)
Post-doc
Faculty at NIT Delhi

yongqi

Liu Yongqi
(Sep 20 - Aug 22)
MPhil student
RA at Xiamen University

haruki

Haruki Saegusa
(Jul 21 - Feb 22)
UG researcher
Student at HKUST

chinmayee

Chinmayee Mallick
(May 20 - Mar 21)
Research Assistant
Research Assistant at PolyU

ellie

Ellie Ong
(Oct 20 - Jan 21)
Visiting scholar
PhD at UNSW

Turnip

Turnip
(Jun 18 - Jun 19)
Boss
Streetcat, stayed in Oxford

bob

Bob
(Feb 18)
Honourary member
🌈