Combining Theory, Models, and Observations
Big Data Oceanography
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Research

I study the physics of the ocean, trying to understand what makes the water move. These are my main research topics.

Ocean Circulation and Mixing

An intricate network of currents circulates water through the global ocean. This circulation is important for Earth's climate because it transports heat, salt, and dissolved chemicals (such as carbon and oxygen) from the surface, where they are in contact with the atmosphere, to the deep abyss, where they can be isolated and stored for centuries or more. One of my main goals is to understand what controls the strength and structure of this global circulation.

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Mesoscale Dynamics

On scales of 10-500 km, the ocean is a twisted tangle of eddies, filaments, and fronts. The behavior of these turbulent flows is dynamically similar to weather systems of the atmosphere. I am fascinated by the complexity of the ocean mesoscale and have made it a central focus of my research. In particular, I would like to gain a better understanding of how energy flows through the mesoscale—how and where eddies extract potential energy from the background flow and how they dissipate their kinetic energy. Better understanding of the mesoscale energy cycle will lead to better representation of sub-grid mixing in climate models.

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Southern Ocean and Climate

The Southern Ocean surrounds Antarctica and connects the other three major ocean basins (Atlantic, Pacific, and Indian). It is the home to the world's strongest current, the Antartic Circumpolar Curent, and is full of mesoscale eddies. Because so much water comes together here, the Souhern Ocean is central to the global circulation, but the intense mesoscale turbulence (and a historical lack of observations), make it very challenging to understand the flow. Improved understanding of the drivers of Southern Ocean circulation will help improve future climate predictions and will also shed light on past climates, such as glacial cycles.

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Big Data Analysis

Scientific datasets are growing in size at an exponential rate, and oceanographic data is no exception. New high-resolution satellite observations and autonomous observing platforms are producing data faster than we can analyze it. Global eddy-resolving ocean models in particular can easily generate terabytes and petabytes of data. Our usual data analysis tools break down when confronted with these data volumes. I am actively engaged in developing open-source software tools to overcome this barrier and enable our community to efficiently process oceanographic Big Data.

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Teaching

I am an assistant professor in the Columbia University Department of Earth and Environmental Sciences. These are the courses I am currently teaching.

Introduction to Physical Oceanography

Physical properties of seawater, ocean water masses and their distribution, sea-air interaction, ocean general circulation, mixing processes.

Geophysical Fluid Dynamics

Fundamental concepts in the dynamics of rotating stratified flows. Geostrophic and hydrostatic balances, potential vorticity, f and beta plane approximations, gravity and Rossby waves, geostrophic adjustment and quasigeostrophy, baroclinic and barotropic instabilities.

Python for Scientific Computing

For the past two years, I have taught an informal introduction to python, designed to take a novice from zero to fully functional in about eight hours. Topics include core python language, IPython notebooks, numpy, matplotlib, Basemap, pandas, and xray.

Papers

Publish or perish.

In Progress / Submitted

  1. Sinha, A., and R. Abernathey, 2016: Timescales of Southern Ocean Eddy Equilibration. | PDF

In Press / Published

  1. Abernathey, R., J. Marshall, E. Shuckburgh, and M. Mazloff, 2010: Enhancement of Mesoscale Eddy Stirring at Steering Levels in the Southern Ocean. J. Phys. Oceanogr., 40, 170–185. | PDF
  2. Abernathey, R., J. Marshall, and D. Ferreira, 2011: The Dependence of Southern Ocean Meridional Overturning on Wind Stress. J. Phys. Oceanogr., 41, 2261–2278. | PDF
  3. Hill, C., D. Ferreira, J.-M. Campin, J. Marshall, R. Abernathey, and N. Barrier, 2012: Controlling Spurious Diapycnal Mixing in Eddy-Resolving Height-Coordinate Ocean Models: Insights from Virtual Deliberate Tracer Release Experiments. Ocean Modelling, 45-46, 14–26. | PDF
  4. Abernathey, R., D. Ferreira, and A. Klocker, 2013: Diagnostics of isopycnal mixing in a circumpolar channel. Ocean Modelling, 72, 1–16. | PDF
  5. Abernathey, R., and J. C. Marshall, 2013: Global surface eddy diffusivities derived from satellite altimetry. J. Geophys. Res., 118, 901–916. | PDF
  6. Gnanadesikan, A., R. Abernathey, and M.-A. Pradal, 2014: Exploring the isopycnal mixing and helium-heat paradoxes in a suite of Earth System Models. Ocean Science Discussions, 11, 2533–2567. | PDF
  7. Klocker, A., and R. Abernathey, 2014: Global Patterns of Mesoscale Eddy Properties and Diffusivities. J. Phys. Oceanogr., 44, 1030–1047. | PDF
  8. Abernathey, R. P., and P. Cessi, 2014: Topographic Enhancement of Eddy Efficiency in Baroclinic Equilibration. J. Phys. Oceanogr., 44, 2107–2126. | PDF
  9. Gnanadesikan, A., M.-A. Pradal, and R. Abernathey, 2015: Isopycnal mixing by mesoscale eddies significantly impacts oceanic anthropogenic carbon uptake. Geophysical Research Letters, 42, 4249–4255. | PDF
  10. Solomon, A., L. M. Polvani, K. L. Smith, and R. Abernathey, 2015: The impact of ozone depleting substances on the circulation, temperature and salinity of the Southern Ocean: An attribution study with CESM1 (WACCM). Geophysical Research Letters, 42, 5547—5555. | PDF
  11. Abernathey, R., and D. Ferreira, 2015: Southern Ocean isopycnal mixing and ventilation changes driven by winds. Geophysical Research Letters, 42, 10,357–310,365. | PDF
  12. Abernathey, R. P., and C. Wortham, 2015: Phase speed cross spectra of eddy heat fluxes in the Pacific. J. Phys. Oceanogr., 45, 1285–1301. | PDF
  13. Bishop, S. P., P. R. Gent, F. O. Bryan, A. F. Thompson, M. C. Long, and R. P. Abernathey, 2016: Southern Ocean Overturning Compensation in an Eddy-Resolving Climate Simulation. Journal of Climate, 46, 1575–1592. | PDF
  14. Wang, L., M. F. Jansen, and R. P. Abernathey, 2016: Eddy phase speeds in a two-layer model of quasigeostrophic baroclinic turbulence with applications to ocean observations. Journal of Physical Oceanography, | PDF
  15. Newsom, E., C. Bitz, F. Bryan, R. P. Abernathey, and P. Gent, 2016: Southern Ocean Deep Circulation and Heat Uptake in a High-Resolution Climate Model. Journal of Climate, | PDF
  16. Abernathey, R., I. Cerovečki, P. R. Holland, E. Newsom, M. Mazloff, and L. D. Talley, 2016: Southern Ocean Water Mass Transformation Driven by Sea Ice. Nature Geoscience, | PDF

Code

Software is the machinery for transforming raw data and ideas into scientific results.

The scientific community is becoming increasingly aware that open access to research code is an essential ingredient for scientific reproducibility and progress. I strive to publish all my resesarch code in online repositories, and I contribute to several open source projects. Python is my weapon of choice.

The projects listed at right represent my reasonably well organized, well documented software packages suitable for general use. In addition, I have lots more code associated with specific papers and research projects available on my github and bitbucket sites.

  •   xgcm

    A python package for the analysis of ocean general circulation model output. Builds on the fantastic xray and dask projets to provide parallel, out-of-core scalability.

  •   pyqg

    A python quasigeostrophic model for turbulence simulations. Well documented and easy to use—ideal for students, but fast enough for real research.

  •   floater

    Python package for turning MITgcm model Lagrangian float output data into PyTables indexed HDF5 files.

  •   MITgcmdata

    Legacy package for working with MITgcm model output data. I am in the process of replacing this with xgcm.

Video

Our human brains excell at identifying patterns from moving images. Video is an essential tool for my science.
See all of my videos on my Vimeo page.

Research Group

These are the people who make the science.

Ryan Abernathey

Assistant Professor

Sjoerd Groeskamp

Postdoc

Anirban Sinha

Grad Student

Takaya Uchida

Grad Student

Omar Mahmood

Undergrad Intern

Other Collaborators

John Marshall
  MIT (Ryan's Ph.D. advisor)
Paola Cessi
  SIO (Ryan's posdtoc advisor)
David Ferreira
  University of Reading
Matt Mazloff
  SIO
Chris Hill
  MIT
Andreas Klocker
  University of Tasmania
Anand Gnanadesikan
  Johns Hopkins
Marie-Aude Pradal
  Johns Hopkins
Cimarron Wortham
  University of Washington
Lorenzo Polvani
  Columbia/LDEO
Ari Solomon
  Columbia
Karen Smith
  LDEO
Emily Newsom
  University of Washington
Cecilia Bitz
  University of Washington
Frank Bryan
  NCAR
Peter Gent
  NCAR
Anirban Sinha
  Columbia
Stuart Bishop
  North Carolina State University
Andrew Thompson
  Caltech
Lei Wang
  University of Chicago
Malte Jansen
  Univerity of Chicago
Ivana Cerovecki
  Scripps Institution of Oceanography
Lynne Talley
  Scripps Institution of Oceanography
Paul Holland
  British Antarctic Survey