About

Mary-Louise Timmermans is the Damon Wells Professor of Earth & Planetary Sciences at Yale University. Her research focuses on ocean dynamics, including the behavior of the Arctic Ocean, ocean circulation, and biogeochemical processes. She has contributed extensively to understanding the Arctic Ocean’s changing systems, including the Beaufort Gyre, sea surface temperature variations, and the ocean’s role in climate change. Her work involves analyzing ocean transport measurements, internal wave-driven mixing, and the impact of stratified shear instabilities on particle sedimentation and carbon removal. Timmermans has also studied the effects of sea ice, ocean mesoscale variability, and the Arctic Ocean’s bathymetry on climate and oceanography. She has authored numerous publications on these topics, advancing knowledge of the physical mechanisms governing ocean and climate interactions.

Research topics

• Environmental science
• Climatology
• Oceanography
• Geology
• Meteorology
• Geography
• Atmospheric sciences
• Computer Science
• Physics
• Mathematics
• Earth science

Selected publications

• Settling and dispersion of Lagrangian particles in the presence of stratified Kelvin-Helmholtz instability and turbulence

  Physical Review Fluids · 2026-01-13

  article
  PublisherDOI

• Mixed Layer Deepening and Internal Wave Generation under Sea Ice in Free Drift

  Journal of Physical Oceanography · 2026-02-11

  articleSenior author

  Abstract The Arctic Ocean stores enough heat to melt the entire sea ice pack, but that heat is isolated from the surface due to strong salinity stratification. Processes like mixed layer deepening and internal wave breaking can erode this stratification and mix heat to the surface. While the deepening of a mixed layer of depth h into an ocean with constant buoyancy frequency N 0 under constant surface forcing is well understood for times (fast deepening; h ∝ t α with α = 0.5), where f is the Coriolis parameter, there is limited consensus on α for t ≳ f −1 (slow deepening). Since f −1 is smallest at polar latitudes, this unsettled regime may be relevant for the Arctic. Moreover, how the amount of energy fluxed into the internal wave field during fast and slow deepening may vary is largely unexplored. Using large-eddy simulations of the ice–ocean boundary layer, we investigate both the rate of slow deepening and the associated internal wave field. We find that sea ice in free drift imposes a nearly constant surface momentum flux on the ocean, even during inertial oscillations. We estimate α = 0.21 for slow deepening, which differs from fast deepening due to the surface power input tending toward a constant over time. Additionally, the resulting internal wave field is weaker during slow deepening because the internal wave energy flux decays as ∼ h −2 . Our results clarify the dynamics of slow deepening and its role in internal wave generation, both in general and in an Arctic context. Significance Statement The purpose of this study is to gain deeper insight into how energy from the atmosphere input at the ice–ocean boundary layer contributes to mixing the upper Arctic Ocean when the dynamics are affected by Earth’s rotation. Using numerical simulations and analytical arguments, we show that Earth’s rotation complicates this energy transfer by modifying the amount of power the ocean receives from the atmosphere. This leads to two distinct dynamical regimes that result in differing degrees of upper-ocean mixing. These results can be used to improve our understanding of how atmospheric forcing can draw stored heat in the Arctic Ocean to the surface, a topic that remains relevant for predicting the future of the Arctic sea ice cover.

  PublisherDOI

• Introduction to the Special Collection on the Arctic Ocean's Changing Beaufort Gyre

  Journal of Geophysical Research Oceans · 2025-07-01 · 4 citations

  articleOpen access1st authorCorresponding

  Abstract The Beaufort Gyre circulation system is a central part of the Arctic climate undergoing significant change in all environmental parameters. This paper presents two decades of intensive observations in the Beaufort Gyre and then introduces the publications that comprise this special collection on the changing Beaufort Gyre. Observations spanning 2003–2024 are analyzed to characterize the Beaufort Gyre's evolving freshwater and heat content, which are related to wind forcing modulated by the presence of sea ice. Following a period of sustained freshwater and heat accumulation in the first half of the record, freshwater and heat content have been declining in recent years. Trends indicate that prevailing winds are changing such that they are becoming less effective at spinning up the gyre and accumulating freshwater. This forcing is dominating over a trend to a weakening sea‐ice pack that is less effective at spinning down the gyre. Details on the changing Beaufort Gyre are examined in the publications in this special collection, including studies on its sea ice, upper‐ocean properties, freshwater sources and content, the fundamental dynamical balances of the Beaufort Gyre, water‐mass circulation, and biogeochemistry. These studies bring new understanding of the Beaufort Gyre that is essential for accurately characterizing the Arctic climate system and informing future projections.

  PublisherOA PDFDOI

• Structure and Evolution of Temperature, Salinity, and Dissolved Oxygen in the Isolated Deep Waters of the Arctic's Canada Basin

  Journal of Geophysical Research Oceans · 2025-10-28

  articleOpen accessSenior author

  Abstract The bottom waters of the Arctic Ocean's Canada Basin are vertically homogeneous and have C isolation age of 450 years. Understanding the evolution of this geothermally heated isolated bottom water and the overlying water layer can provide insights into Arctic circulation patterns, including interactions between shallow and deep waters, as well as past climate conditions that may have resulted in their isolation. Observations of deep and bottom‐water potential temperature , salinity , and dissolved oxygen from the Beaufort Gyre Observing System/Joint Ocean Ice Study (BGOS/JOIS) program are analyzed in context with property conservation equations, geothermal heating, vertical diffusion, and biological consumption. We find an approximately linear warming trend of the bottom waters over 2003–2024, updating a previous study ending in 2010. We additionally find trends of decreasing salinity and dissolved oxygen over the record. The structure of the bottom water varies spatially, with thinner, warmer, and fresher bottom waters with lower observed near the boundaries. Bottom‐water properties are fluxed vertically into an overlying potential temperature minimum layer, with enhanced vertical fluxes of heat, salt, and dissolved oxygen in turbulent regions near the basin boundaries, and lower, likely molecular vertical fluxes in the basin interior. Heat is fluxed laterally in the layer from the boundaries to the interior, resulting in approximately spatially uniform rates of warming of the layer. Over 2005–2024, decreasing bottom‐water suggests an important influence of organic matter remineralization. The findings in this study are consistent with continued isolation of bottom waters.

  PublisherOA PDFDOI

• Can the Marked Arctic Ocean Freshwater Content Increases of the Last Two Decades Be Explained Within Observational Uncertainty?

  Journal of Geophysical Research Oceans · 2025-02-01 · 3 citations

  articleOpen accessSenior author

  Abstract The freshwater content of the Arctic Ocean has increased dramatically in the last two decades, particularly in the Beaufort Gyre. However, quantifying the sources of this change is an observational challenge and has historically been limited by methodological differences across studies. Here we derive observation‐based freshwater budgets from volume and mass budgets for the Arctic Ocean and the Beaufort Gyre from 2003 to 2020. Our budgets include all sources and sinks (river runoff, precipitation minus evaporation, land ice melt, sea ice export, sea ice melt, and ocean fluxes) as well as volume and mass storage terms measured by satellite. We find that Arctic freshwater changes are dominated by changes in the Beaufort Gyre, and we reconcile this with previous studies that argue for freshwater compensation between the Beaufort Gyre and the rest of the Arctic. We use inverse methods to close the volume and mass budgets within observational uncertainty and link the observed Arctic freshwater changes to the sources and sinks. Our budget analysis demonstrates that small changes to the ocean fluxes (smaller than we can measure) can account for all freshwater storage changes in the Arctic, highlighting the need for more careful accounting and detailed ocean observations in this rapidly changing environment.

  PublisherOA PDFDOI

• Arctic Ocean bathymetry and its connections to tectonics, oceanography and climate

  Nature Reviews Earth & Environment · 2025-03-06 · 8 citations

  review
  PublisherDOI

• Investigating the Relative Roles of Dynamics and Thermodynamics in Sea‐Ice Volume Changes in the Canada Basin

  Journal of Geophysical Research Oceans · 2025-02-01 · 2 citations

  articleSenior author

  Abstract The Canada Basin (CB) has seen significant sea‐ice loss in recent decades. We use output from the Pan‐Arctic Ice‐Ocean Modeling and Assimilation System to examine the 1979–2023 evolution of seasonal sea‐ice volume (SIV) changes in the CB partitioned into advective and thermodynamic changes. In winter, some years show net convergence into the region that is of comparable magnitude to the SIV change attributed to sea‐ice growth. In summer, melt/ablation dominates the change each year. In both seasons, 44 year trends in seasonal SIV changes are driven primarily by thermodynamic processes. The inferred thermodynamic growth each year is nearly equal to the inferred melt consistent with SIV at the end of the melt season declining more rapidly than SIV at the end of the growth season. Increased melt season atmospheric heating of the ice‐ocean system over 1979–2023, estimated from ERA5 reanalysis, is consistent with the ice‐albedo feedback. In the growth season, net cumulative atmospheric heat release from the ice‐ocean system shows no trend, suggesting increases in inferred thermodynamic ice growth can be attributed to more rapid growth of thinner ice. In each season, cumulative atmospheric heat input exceeds that required for ice melt/growth resulting in a residual that influences ocean heat content (OHC). Seasonal OHC changes, inferred from ocean observations, are equal to approximately one‐third of this residual, although limited ocean observations leave the total heat budget poorly constrained, highlighting a need for more water column observations.

  PublisherDOI

• Influence of stratified shear instabilities on particle sedimentation in three-dimensional simulations with application to marine carbon dioxide removal

  Physical Review Fluids · 2025-01-10 · 4 citations

  article

  Stratified flow instabilities play a critical role in particle sedimentation in marine environments, influencing the efficacy of marine carbon dioxide removal strategies. Using direct numerical simulations, we reveal how these instabilities enhance or inhibit settling across flow regimes. Our findings highlight the dynamic interplay between turbulence, stratification, and particle dynamics, providing new insights into optimizing carbon removal techniques.

  PublisherDOI

• Global Ocean <i>p</i>CO₂ Variation Regimes: Spatial Patterns and the Emergence of a Hybrid Regime

  Journal of Geophysical Research Oceans · 2024-05-01 · 4 citations

  articleOpen accessSenior author

  Abstract The variability in ocean surface partial pressure of carbon dioxide ( p CO 2 ), driven by both physical and biological processes, substantially influences air‐sea carbon exchange. It is widely recognized that the p CO 2 variation at a specific ocean location is primarily dominated by either thermal or nonthermal effects. However, the distinct p CO 2 variation regimes, their global distribution, and the mechanisms underlying such patterns have yet to be fully determined due to a paucity of global observations. Through the use of observation‐based products and an eddy‐resolving ocean simulation, this study demonstrates the presence of three distinct regimes in the global ocean: one in which sea surface temperature (SST) is the dominant control on p CO 2 variations; another in which dissolved inorganic carbon (DIC) is the primary control; and a third previously uncharacterized hybrid regime where p CO 2 variations are governed by seasonally‐varying factors. This hybrid regime is generally located between SST‐ and DIC‐dominated regimes and occupies approximately 15% of the global ocean. The regimes broadly exist in zonal bands that are closely linked to the relative strengths of SST and DIC variances. Seasonally‐varying mixed‐layer depth, mesoscale variability (quantified in terms of eddy kinetic energy), and biological processes modulate local p CO 2 variations and play significant roles in shaping the global pattern of regime distributions. Understanding the distribution of p CO 2 regimes, including the hybrid regime revealed in this study, as well as their different oceanic drivers, is essential for future predictions of ocean carbon uptake in response to global warming.

  PublisherOA PDFDOI

• The Role of Ocean Mesoscale Variability in Air‐Sea CO₂ Exchange: A Global Perspective

  Geophysical Research Letters · 2024-05-15 · 12 citations

  articleOpen accessSenior author

  Abstract Ocean mesoscale flows significantly influence nutrient distribution and biological productivity, yet the scarcity of eddy‐permitting observational data sets and climate modeling hinders understanding their role in carbon sequestration. Using an eddy‐resolving global simulation, this study investigates the significance of ocean mesoscales in air‐sea carbon dioxide (CO 2 ) exchange. Results show over 30% of CO 2 flux variance in energetic regions attributed to flows with horizontal scales smaller than 2°. Mesoscale flows can drive a cumulative CO 2 flux that is either a net carbon sink or source depending on region, with magnitudes on the order of 10 5 tonnes of carbon per year. Variations in this mesoscale‐related CO 2 flux are correlated with local relative vorticity and the background gradient of ocean partial pressure of CO 2 . This analysis underscores the importance of considering ocean mesoscales in monitoring carbon flux, highlighting the need to explore the influence of increasing eddy activity on carbon uptake in a changing climate.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Quantifying the Residual Circulation of the Arctic Ocean

  NSF · $184k · 2016–2019

• COLLABORATIVE RESEARCH: Observing and characterizing submesoscale dynamics in the Arctic Ocean

  NSF · $244k · 2011–2015

• The Role of Anticyclonic Eddies in the Arctic Halocline

  NSF · $209k · 2007–2009

• CAREER: Evolution and Dynamics of the Deep Waters in the Arctic Ocean

  NSF · $604k · 2014–2019

• AON Collaborative Research: Continuation of long-term Beaufort Gyre observations in 2020-2024 to enhance understanding of the Arctic's role in climate variability

  NSF · $666k · 2020–2026

Frequent coauthors

• Richard Krishfield

  Woods Hole Oceanographic Institution

  46 shared

• John M. Toole

  41 shared

• Andrey Proshutinsky

  Woods Hole Oceanographic Institution

  40 shared

• Jhan Carlo Espinoza

  Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

  22 shared

• Bertrand Decharme

  22 shared

• N. I. Shiklomanov

  20 shared

• Nicole C. Shibley

  Princeton University

  20 shared

• Kaisa Lakkala

  Finnish Meteorological Institute

  20 shared