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.
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.
Welcome (again) to Floriane who has joined as a CORE funded post-doc, working on various analyses relating to heat, nutrients and blooms in the ocean.
Han Seul defended her PhD thesis "The Role of Eddy Effects in the Sensitivity of the Southern Ocean Circumpolar Current to Changes in Wind Stress" respectively in Sept 2025. Many thanks to the examiners and particularly the external examiner Chen Ru. Han Seul is starting a post-doc in Universite Catholique de Louvain in Belgium.
Yongsu defended his PhD thesis "State Estimation and Adjoint Sensitivity Analysis in the South China Sea" in Aug 2025. Many thanks to the examiners and particularly the external examiner Dave Stevens. Yongsu is starting a post-doc at OIST in Japan.
Welcome to Jiahui and Samantha joining as MPhil students this year! Jiahui will be looking at transient/non-normal fluid instabilities, and Samantha will be looking to analyse regional variations of Ocean Heat Content and contributions to sea level.
Virryna 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 2025 as a visitor at LOPS (part of IFREMER) at Brest, working on Arctic oceanography related research.
Bobo has defended her PhD thesis "Combined Physical and Biogeochemical Assessment of Mesoscale Eddy Parameterisations in Ocean Models Across Resolutions" in May 2025. Many thanks to the examiners and particularly the external examiner Chai Fei. Bobo is staying for another six months as a post-doc for the time being.
Julian joined as a co-chair of the NEMO eddy parameterisation working group from April 2025.
Fei Er has defended her PhD thesis "The Application of Machine Learning in Parameterizing Geostrophic Turbulence" in March 2025. Many thanks to the examiners and particularly the external examiner Liu Lin. Best of luck in your next position as a post-doc in Columbia University!
Julian joined the editorial board of EGU Ocean Sciences from August 2024.
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.
R. Torres^, R. Waldman, G. Madec, C. de Lavergne, R. Séférian & J. Mak (2025) [doi]
J. Adv. Model. Earth Syst., 17(12), e2025MS005394
H. S. Lee, J. R. Maddison, J. Mak, D. P. Marshall & Y. Wang (2025) [doi]
Tellus A, 77(1), 199-220
F. E. Yan, H. Frezat, J. Le Sommer, J. Mak & K. Otness (2025) [doi]
J. Adv. Model. Earth Syst., 17(7), e2024MS004857
J. R. Maddison, D. P. Marshall, J. Mak & K. Maurer-Song (2025) [doi]
J. Adv. Model. Earth. Syst., 17(4), e2024MS004682
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.
X. Ruan, D. Couespel, M. Lévy, J. Li, J. Mak & Y. Wang (2024) [doi]
Ocean Modell., 190, 102396
J. Mak, J. R. Maddison, D. P. Marshall, X. Ruan, Y. Wang & L. Yeow (2023) [doi]
J. Adv. Model. Earth. Syst., 15(12), e2023MS003886
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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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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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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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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Associate Professor + senior code monkey (since Jul 2025)
Assistant Professor + code monkey (Jul 2019 -- Jun 2025)
Senior NOC fellow (since Sep 2023)
The group's code-fixer. See personal website for proper content.
Favourite fish: Ducks
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.
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.
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.
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.
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.
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.
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.
Han Seul Lee
(Sep 19 - Sep 25)
PhD student
PDRA at Universite Catholique de Louvain
Yongsu Na
(Sep 20 - Aug 25)
PhD student
PDRA at OIST
Fei Er Yan
(Feb 21 - Mar 25)
PhD student
PDRA at Columbia University
Dan Bartley
(Sep 22 - Aug 24)
MPhil student
PhD at Imperial College
Wang Huanhuan
(Sep 22 - Feb 23)
Post-doc
RA at HKU
Gautam Kumar
(Mar 21 - Sep 22)
Post-doc
Faculty at NIT Delhi
Liu Yongqi
(Sep 20 - Aug 22)
MPhil student
RA at Xiamen University
Haruki Saegusa
(Jul 21 - Feb 22)
UG researcher
Student at HKUST
Chinmayee Mallick
(May 20 - Mar 21)
Research Assistant
Research Assistant at PolyU
Ellie Ong
(Oct 20 - Jan 21)
Visiting scholar
PhD at UNSW
Turnip
(Jun 18 - Jun 19)
Boss
Streetcat, stayed in Oxford
Bob
(Feb 18)
Honourary member
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