About

Thomas Haine’s research interests are in ocean circulation and dynamics, and the ocean’s role in climate. He is involved in improving estimates of the geophysical state of the ocean circulation through analysis of field data and circulation model results. He is particularly interested in the high latitude oceans, including the subpolar North Atlantic, Arctic, and Southern Oceans. He studies watermass ventilation processes (rates, pathways, variability, and mechanisms), three-dimensional circulation, and geophysical fluid dynamics. He also investigates key physical processes that maintain the state of the extra-tropical upper ocean focusing on fluid dynamics and thermodynamics and their role in controlling sea surface temperature variability over years to decades. Current research in Prof. Haine’s group addresses Arctic/North Atlantic dynamics, geophysical fluid dynamics, computational oceanography, passive tracer and transport diagnostics, and pedagogical oceanography.

Research topics

• Environmental science
• Climatology
• Geology
• Oceanography
• Geography

Selected publications

• Influence of Subinertial Variability on Dense Overflows Across the Iceland–Faroe Ridge

  2026-05-14

  articleOpen accessSenior author

  Subinertial variability increases Iceland-Faroe Ridge overflow transport and more than doubles downstream overflow particle export. Subinertial variability shifts overflow pathways toward direct export rather than detours or recirculation through neighboring channels. Changes in pathway partitioning alter temperature-salinity evolution sampled by dense overflow particles during downstream descent.

  PublisherOA PDFDOI

• Remineralisation changes dominate oxygen variability in the North Atlantic

  Ocean science · 2026-01-20

  articleOpen access

  Abstract. Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing biodiversity, and disrupting biogeochemical cycles. In recent decades, the global ocean oxygen concentration has been decreasing, but this decrease is underestimated in numerical ocean models by as much as 50 %. Mechanisms responsible for this deoxygenation include (i) solubility-driven deoxygenation due to ocean warming, and (ii) changes in the remineralised signal due to either a change in the supply of biological material to depth or a change in circulation leading to change in the residence time of water, and hence the accumulation of the remineralised oxygen deficit, or a combination of both. The magnitude of oxygen change due to each process is currently unclear. Here, we describe and implement a new method to decompose oxygen change into its constituent parts by linking each process to concomitant changes in temperature and dissolved inorganic carbon. Using observations on a repeated section of the North Atlantic at 24.5° N, we show that the consistent oxygen decrease observed since 1992 in the upper 2000 m has been dominated by an increase in remineralisation-related oxygen-consumption. While warming-driven solubility changes have a much smaller impact on the upper ocean in comparison, their impact has trebled in the past twenty years, suggesting they will become an increasingly significant driver of deoxygenation with future warming. Remineralisation-related oxygen consumption peaks at a depth of approximately 600 m, where it is responsible for up to 70 % of the total deoxygenation. While this study does not determine the exact cause of the remineralisation-driven change, little change in primary productivity has been observed in the region, suggesting that a change in ocean circulation is indirectly driving the majority of deoxygenation in the Subtropical North Atlantic, via a non-local change in remineralisation.

  PublisherOA PDFDOI

• A Review of Green's Function Methods for Tracer Timescales and Pathways in Ocean Models

  Journal of Advances in Modeling Earth Systems · 2025-07-01 · 2 citations

  reviewOpen access1st authorCorresponding

  Abstract Understanding advective‐diffusive dispersal of trace substances in environmental fluids like the global ocean is a ubiquitous challenge in geophysics. Since the turn of the millennium, substantial progress has been made in the theory, implementation in models, and application of such tracers in oceanography. For the first time, this progress is reviewed here in a synthetic way. We focus on tracer techniques in ocean models, including real and virtual tracers that diagnose timescale information, and we emphasize the connection to the Green's function that solves the advection‐diffusion equation. Implementation of these techniques in ocean models is explained in an accessible way. We present example applications of these techniques to questions concerning ocean circulation, transport of biogeochemicals, and paleoceanography, including future opportunities.

  PublisherDOI

• Tracer Budgets on Lagrangian Trajectories

  2025-01-28

  preprintSenior author

  The Lagrangian particle method is widely used to understand scalar tracer concentra- tion fields in models of the atmosphere and oceans. Simulating virtual particles provides an alternative description of advection to the Eulerian representation in models and aids in identifying pathways, timescales, and connectivity. Atmospheric and oceanic models solve advection-diffusion-reaction equations to simulate tracers, in which only the ad- vective component is captured by traditional Lagrangian approaches. In this work, we report a novel method that closes tracer budgets on Lagrangian trajectories in a man- ner consistent with Eulerian budgets in finite-volume models. The scalar tracer concen- trations on grid cell walls are derived from the model advection scheme and then inter- polated inside grid boxes along streamlines. The divergence of the diffusive flux and re- action terms are interpolated based on velocity and tracer concentration, ensuring the tracer budget closes in terms of both trajectory and volume integrals. We demonstrate the method using a case study of Southern Ocean biogeochemistry. Another case study involves analyzing the heat budget of the 2011 Western Australian marine heat wave. The method bridges the gap between Eulerian budget and Lagrangian particle analy- ses by representing the advective processes with particle movements and interpolating the diffusive and reactive processes onto trajectories in a way consistent with the finite- volume description.

  PublisherDOI

• Generation and propagation of Eastern Subpolar North Atlantic salinity anomalies

  Research Square · 2025-09-04

  preprintOpen accessSenior author
  PublisherOA PDFDOI

• Tracer Budgets on Lagrangian Trajectories

  Journal of Advances in Modeling Earth Systems · 2025-09-01

  articleOpen accessSenior author

  Abstract The Lagrangian particle method is widely used to understand scalar tracer concentration fields in models of the atmosphere and oceans. Simulating virtual particles provides an alternative description of advection to the Eulerian representation in models and aids in identifying pathways, timescales, and connectivity. Atmospheric and oceanic models solve advection‐diffusion‐reaction equations to simulate tracers, in which only the advective component is captured by traditional Lagrangian approaches. In this work, we report a novel method that closes tracer budgets on Lagrangian trajectories in a manner consistent with Eulerian budgets in finite‐volume models. The scalar tracer concentrations on grid cell walls are derived from the model advection scheme and then interpolated inside grid boxes along streamlines. The divergence of the diffusive flux and reaction terms are interpolated based on velocity and tracer concentration, ensuring the tracer budget closes in terms of both trajectory and volume integrals. Compared to the Eulerian budget analysis, which considers a fixed volume, our method quantifies the tracer evolution within a volume that moves along with the flow. We demonstrate the method using a case study of Southern Ocean biogeochemistry. Another case study involves analyzing the heat budget of the 2011 Western Australian marine heat wave. The method bridges the gap between Eulerian budget and Lagrangian particle analyses by representing the advective processes with particle movements and interpolating the diffusive and reactive processes onto trajectories in a way consistent with the finite‐volume description.

  PublisherDOI

• Remineralisation changes dominate oxygen variability in the North Atlantic

  2025-08-18

  articleOpen accessCorresponding

  Abstract. Oxygen is fundamental to ocean biogeochemical processes, with deoxygenation potentially reducing biodiversity, and disrupting biogeochemical cycles. In recent decades, the global ocean oxygen concentration has been decreasing, but this decrease is underestimated in numerical ocean models by as much as 50 %. Mechanisms responsible for this deoxygenation include solubility-driven deoxygenation driven by ocean warming, and changes in the amount, rates and spatial patterns of remineralisation. However, the magnitude of change in oxygen due to each process is currently unclear. Here, we use a new method to decompose oxygen change into its constituent parts by linking each process to concomitant changes in temperature and dissolved inorganic carbon. Using observations across a repeated section of the North Atlantic at 24.5° N, we show that the consistent oxygen decrease observed since 1992 in the upper 2000 m has been dominated by an increase in remineralisation-related oxygen-consumption. While warming-driven solubility changes have a much smaller impact on the upper ocean in comparison, the impact has trebled in the past twenty years, suggesting they will become an increasingly significant driver of deoxygenation with future warming. Remineralisation-related oxygen consumption peaks at a depth of approximately 600 m, where it is responsible for up to 70 % of the total deoxygenation. This remineralisation-driven change may be caused by a change in the supply of biological material to depth, a change in circulation leading to change in the residence time of water in the North Atlantic and hence the accumulation of the remineralised oxygen deficit, or a combination of both. While this study does not determine the exact cause, previously little change in productivity in has been observed in the region, suggesting ocean circulation is indirectly driving the majority of deoxygenation in the Subtropical North Atlantic, via a non-local change in remineralisation.

  PublisherOA PDFDOI

• Democratize the Data: A New Way to Analyze and Design Ocean Models

  Oceanography · 2025-01-01 · 1 citations

  articleOpen access1st authorCorresponding

  Ocean circulation models running on the latest supercomputers can cover the globe with resolutions of a few kilometers. These virtual ocean datasets are increasingly realistic and provide insight into processes at scales that are inaccessible with conventional observations. Because these datasets are far too massive for individual researchers to download and analyze, new cloud-based, open-source, cyberinfrastructure resources are being developed. These tools provide a new analysis paradigm that is scalable, accessible, and inclusive, and that democratizes access to ocean circulation model output. They also accelerate the pace of analysis of ocean models and thereby increase the pace of discovery in oceanography. Another challenge concerns the priorities for next-generation ocean circulation models. In particular, to improve circulation model simulations, how should increased supercomputer power be spent? Input on this question from the oceanographic community is sought.

  PublisherOA PDFDOI

• Coupled air-sea interaction drove and sustained the 2013–2016 North Pacific Marine Heatwave

  Research Square · 2025-10-13

  preprintOpen accessSenior author
  PublisherOA PDFDOI

• Role of Sea Ice and Ocean in the Observed Increase in Arctic Liquid Freshwater Content

  Journal of Climate · 2025-06-25

  article

  Abstract While the Arctic sea ice has declined, the Arctic Ocean has accumulated significant liquid freshwater in the past two decades. These changes in the Arctic freshwater system are controlled by naturally occurring climate variability and anthropogenically forced changes involving meteoric, sea ice, and oceanic freshwater sources. This study elucidates the mechanisms of the increase in the Arctic liquid freshwater content and investigates the role of sea ice and ocean in modulating the increase using a large ensemble of fully coupled simulations and an atmospheric forced ocean–sea ice simulation within the Community Earth System Model framework. The freshening of the upper Arctic Ocean since the mid-1990s has been primarily caused by anthropogenically driven changes in the sea ice cycle, resulting in an anomalous increase in freshwater passing from the solid phase into the liquid phase. Natural variations in the ocean circulation impact the spatial distribution of the increase, moving it from the Eurasian into the Canadian basin. The contrasting changes in oceanic freshwater fluxes and their volume transport- and salinity-driven contributions in the two configurations suggest that these responses are subjected to significant oceanic variability. Additionally, the differences in river runoff responses in the two types of simulations indicate potential deficiencies in the coupled model representation of the land hydrological cycle. Significance Statement The Arctic Ocean has gained significant liquid freshwater in the last two decades. This study aims to understand this increase and its connection to changes in the Arctic climate. It found that human-driven changes in sea ice have primarily caused the freshening of the upper Arctic Ocean, while natural variations in ocean circulation affect the spatial distribution of the freshwater increase. However, identifying the human impact on freshwater transports through the Arctic Ocean gateways using climate model simulations is challenging, given the uncertainties in climate models, initial conditions, and ocean–atmosphere coupling.

  PublisherDOI

Recent grants

• Collaborative Research: Transport Timescales, Pathways, and Carbon Uptake in the North Atlantic Ocean

  NSF · $542k · 2003–2007

• Petascale Arctic Atlantic Antarctic Virtual Experiment

  NSF · $736k · 2009–2014

• Collaborative Research: Framework: Data: Toward Exascale Community Ocean Circulation Modeling

  NSF · $1.9M · 2018–2023

• Collaborative Research: Mechanisms of Freshwater Exchange Across the East Greenland Shelf

  NSF · $372k · 2014–2019

• CMG: Quantifying Uncertainty in Oceanic State Estimation

  NSF · $620k · 2005–2011

Frequent coauthors

• Renske Gelderloos

  48 shared

• Mattia Almansi

  National Oceanography Centre

  43 shared

• John Marshall

  Massachusetts Institute of Technology

  39 shared

• S. Lee

  Millersville University

  37 shared

• Amit Tandon

  University of Massachusetts Dartmouth

  37 shared

• Raymond G. Najjar

  37 shared

• Todd D. Sikora

  Millersville University

  37 shared

• J. Botella

  Massachusetts Institute of Technology

  37 shared

Labs

• Haine LabPI