Morton K. Blaustein Chair and Professor of
Ocean Circulation and Dynamics; Ocean's role in Climate
My overall research interest is the fundamental understanding of the physics of the basin-scale ocean and its role in Earth's climate. I am involved in improving estimates of the geophysical state of the ocean circulation through analysis of field data and circulation model results. The subpolar North Atlantic ventilation process (rates, pathways, variability, and mechanisms) interests me in particular. I also investigate 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.
Knowledge of these processes is vital if we are to describe and understand climatic fluctuations on time-scales of years to decades. At these low frequencies one must accept that the ocean and atmosphere are components of a coupled system. Understanding low frequency natural climate perturbations is clearly a problem of special current relevance. Further, explaining natural climate variability is a pre-requisite of addressing man-kind's effect on global climate.
K. Blaustein Chair and Professor of Earth
& Planetary Sciences, Johns Hopkins
Current Research Projects | Talks | Group | Classes | News | Preprints & Publications
Current Research Projects
Tracers & Transport Diagnostics
We aim to identify and understand the tracer-independent transport information contained in ocean tracer data. With collaborators, I have developed some new, powerful theoretical tools and I am applying them to diagnose transport timescales and water-mass composition in the North Atlantic ocean. We are also exploiting the ideas to estimate the oceanic burden of anthropogenic carbon - the new methods have distinct advantages. My long-term aim is to synthesize these ideas about passive tracer transport with potential vorticity theories (that is, dynamically-active tracer theories) of the ocean general circulation.International Workshop / School on Tracer and Timescale Methods for Understanding Complex Geophysical and Environmental Processes, Louvain-la-Neuve, Belgium.
Our latest work is focused on interpreting time-lagged correlations from oceanographic timeseries data.
Subpolar Atlantic Circulation & Dynamics
The goal is to better understand the circulation and dynamics of the Denmark Strait, East Greenland Shelf, and Irminger Sea. Diagnosing and monitoring the flow in this area is critical to estimate the state and variability of the meridional overturning circulation in the North Atlantic ocean. My approach is to use high-resolution numerical models, state-of-the-art data assimilation, and collaborate with observational oceanographers and atmospheric scientists working this area.
This project contributes to the international Arctic-Subarctic Ocean Flux (ASOF) study: I am chair of the International Scientific Steering Group for this program.
Some recent animations of our 2km, 97-level simulation of overflow through Denmark Strait are here (from High-frequency fluctuations in Denmark Strait transport) and here (from On the nature and variability of the East Greenland Spill Jet: A case study in summer 2003).
We're particularly interested in the role of sub-mesoscale atmospheric motions on subpolar ocean circulation, and collaborate with atmospheric scientists on this topic. See this clip for an impression of the Irminger Sea atmospheric boundary layer from the FAAM research aircraft at 100feet!
See our project page on: Pathways and transformation of the Denmark Strait Overflow Water in the Irminger Basin.
Recently, we've started working on a collaborative project to quantify and understand the role of the warming ocean on melt of Greenland's glaciers. The new project page is: Submarine Melting of Greenland's Glaciers: What are the Relevant Ocean Dynamics?
I'm also interested in the environmental knowledge of Norse colonists to Iceland, Greenland and North America in the middle ages.
I work on this topic with Mike Spall, Kial Stewart, Marcello Magaldi, Inga Koszalka, Alex Fuller, Bob Pickart, Fiamma Straneo, researchers at the Oceans & Climate group of GFDL and the Greenland Flow Distortion Experiment.
Geophysical Fluid Dynamics
We want to understand the dynamics of rotating stratified fluids in laboratory experiments involving non-linear interactions. Fascinating measurements by Paul Williams shows that large-scale, low-frequency balanced motions can spontaneously emit short fast waves in a laboratory experiment (see this movie). This presents a challenge to theorists who have quite strong evidence that this should not occur. We are trying to understand what's going on.
Fundamental Ideas in Climate Sensitivity
Aim: To identify and understand the dynamic and thermodynamic mechanisms controlling midlatitude interannual SST variability. My focus is on internal ocean processes (advection, mixing, and waves) and their ability to carry signals from remote places in space and time. The ventilation process (see above) has a leading part to play. There are several fundamental issues about how these control mechanisms might operate, or even be described. Interestingly, this issue is closely related to problems in solid state theory and statistical physics. These topics all have roots in the theory of non-equilibrium dynamical systems. This subject is another area of interest for me.
Teaching Rotating Stratified Fluid Dynamics
To explore and develop the use of rotating tank experiments in undergraduate teaching of oceanic and atmospheric science. To visit schools and talk about oceans, atmospheres, climate, and high-latitude exploration.
I work on this topic with the Deepak Cherian, who was an undergraduate intern in my group in 2009, Robbie Nedbor-Gross and the Weather in a Tank team based at MIT. See our recent article on gyroscopes in the Bulletin of the American Meteorological Society.
Schools (and grades) I've visited:
Biophysical Controls on CDOM
We aim to diagnose and understand the physical and biogeochemical processes affecting colored dissolved organic matter (CDOM), especially in the high latitude oceans.
I work on this topic with the Suneet Dwivedi and Carlos Del Castillo at Johns Hopkins Applied Physics Laboratory. We are involved with the Southern Ocean GasEx project.
Our 2012 Ocean Sciences poster is here and our latest manuscript is here.
The SOGasEx project recently won a NASA Group Achievement Award!
Much of our research involves comparing numerical circulation models with observations. I have two clusters of linux workstations to perform the demanding calculations, we also use other clusters and national supercomputer centers for our work. Please contact me for access to our model results. I'm a member of the Hopkins Institute for Data Intensive Engineering & Science (IDIES) and a committee member of the Homewood High-Performance Cluster (HHPC).
Our projects are sponsored by the National Science Foundation, National Aeronautics and Space Administration, Johns Hopkins University, and the National Oceanic & Atmospheric Agency. We greatly appreciate their support! (Any opinions, findings, and conclusions or recommendations expressed in this material are my own and do not necessarily reflect the views of these agencies).
See these talks by Tom:
April 2010 lecture "Transit-time distributions: A tool to diagnose rates and pathways of tracer transport in advective/diffusive flow" at the Institute for Mathematics and its Applications workshop on "Transport and Mixing in Complex and Turbulent Flows," University of Minnesota.
April 2010 tutorial lecture on "Introduction to
dynamics and tracer dispersion in geophysical fluids" at the Institute for Mathematics and its
Applications Workshop on "Transport and Mixing in
Complex and Turbulent Flows."
February 2014 talk on "Analogies of Ocean/Atmosphere Rotating Fluid Dynamics with Gyroscopes-Teaching Opportunities" at American Meteorological Society Annual Meeting.
May 2014 talk on "Greenland
Norse Knowledge of the North Atlantic" at "Culture
and Arctic Climate Change: A Scoping Workshop to Explore
Integrative Frameworks", Yale University.
October 2014 talk on "Diagnosing sea-surface temperature dynamics from stochastically-forced fluctuations" at the Institute for Pure & Applied Mathematics workshop on "Turbulent Transport and Mixing", UCLA.
Former PhD Students:
Former Post Docs:
Prospective students: I look for curious, motivated and creative students who are interested in physical oceanography and have very good skills in physics, applied mathematics, fluid dynamics, and/or scientific computing. If you think you fit this description and are interested in our research please contact me directly about opportunities: I'm always looking for good students. The unique environment at EPS and in CEAFM gives unrivaled opportunities for fundamental research in physical oceanography with connections to climate dynamics and fluid mechanics. The chance to pursue a CEAFM dual-degree in another JHU department is a particular strength of our world-class program. Packages covering 100% tuition and stipend are available!
In Spring 2015 I'm co-teaching 270.224 Oceans
Preprints & Publications
My google scholar page (with links to all publications).
Recent full CV with full publication list.