H. Thomas Rossby

  • Emeritus Professor of Oceanography
  • Physical Oceanography
  • Phone: 401.874.6521
  • Email: trossby@uri.edu
  • Office Location: 222 Watkins
  • Website

You can visit his blog here: mrtomsblog.com


Dr. Thomas Rossby may be a professor emeritus at GSO but he is anything but fully retired.

“My activities are of two kinds,” he writes, “science and technology.”

Indeed, Rossby has his name connected with myriad devices that are commonly used today to gather oceanographic data, some via very economical ways.

Born in Boston, son of a Swedish father and American mother, Rossby spent most of his growing years in Sweden. He attended the Royal Institute of Technology and studied for a degree in technical physics. When he came to the U.S. to work (he was all along an American citizen) family members pushed him to attend graduate school and he went to MIT to get a doctorate in oceanography.

Throughout his life he coupled his love for technology with science (“I love the engineering”). He has been involved in various floats (free-floating instruments that drift at depth), the inverted sounder and an isopycnal float, which can track fluid motion in the horizontal and vertical as density surfaces in the ocean move up and down. One major tool he has used extensively is the acoustic Doppler current profiler (ADCP). Installed in merchant vessels, these instruments profile ocean currents as they repeatedly traverse the various shipping lanes. This repeat sampling is crucial if we want to get an idea of oceanic change and variability.  Vessel operators welcome the idea of being useful to science “as long as we don’t disturb them,” he says.

A lot of Rossby’s research has to do with the Gulf Stream. “With our float work, we have learned about how water streams along the current, where and how water is exchanged with its surroundings. With hydrography we have learned about the long-term stability of the current and its role in transporting heat from low to high latitudes. Using ships we have learned about the structure of the current, its strength and variability over a wide range of time scales.

“Most recently we have a paper noting the stability of Gulf Stream transport on long-time scales,” he adds noting that transport varies from year to year but contrary to what some researchers think they have seen “we have not detected any slow-down in transport. Of course, that says nothing about what will happen in the future.”

Among his studies, Rossby says the investigation of the so-called “meddy” off the Bahamas was one of the most intriguing. A meddy or “lens” is a clockwise swirling mass of water that has higher temperature and salinity than the surrounding waters. This meddy was about 100km in diameter and was centered at a depth of about 1,000m. At first it was theorized that the meddy originated from the Mediterranean but further studies showed otherwise. Subsequent studies showed that meddy-like structures are commonplace in the ocean.

Because of his success in obtaining data with instrumentation aboard merchant vessels, Rossby thinks GSO should do more of it. “It is an area I think GSO should take an active leadership role in. There is a big future here for the simple reason that vessels in regular service sample the same body of water over and over again. We have shown the science to come out of this activity to be of cutting-edge quality.”

Starting in 1995 and continuing until recently Rossby has been a frequent guest investigator at the University of Stockholm, an activity that has led to a number fruitful studies.


Physical Oceanography

Circulation, Climate change and ocean circulation, Current measurements, Instrumentation, Measurements from ships of opportunity, Observational oceanography, Observational physical oceanography, Observations of mixing and circulation, Ocean circulation, Ocean current measurements, Ocean policy and education. 

My activities are of two kinds, science and technology. Over the years I have been involved with the development of a number of enabling (mostly to measure currents) technologies, including the Lagrangian SOFAR and RAFOS floats, the profiling Pegasus and Yvette instruments, the inverted sounder (taken over and developed into the fantastic system Randy Watts operates today). A major step forward was the development of the isopycnal float – a float that tracks fluid motion in both the horizontal and vertical (as density surfaces move up and down). This is something I’m particularly proud of.

I also initiated the URI sound source development (patent shared with Jim Miller) and its subsequent fabrication for a number of years, and the fish-chip with Godi Fischer as the lead PI.

The science that has come out of these activities has been considerable. In no small measure thanks to these developments, we now know far more about the structure of ocean currents, ranging from major systems like the Gulf Stream from Cape Hatteras to the northern Norwegian Sea, of coherent eddy motion whether Gulf Stream rings, meddies and their cousins, or permanent features such as the remarkable Lofoten eddy in the middle of the Lofoten Basin at 70°N (a paper that just came out in JGR).

Much of my time in recent years has been devoted to working with the merchant marine for scanning ocean currents. The data from these vessel-mounted ADCPs have enabled us to examine the dynamical structure of ocean currents in amazing detail, kind of like conducting CAT-scans except better, because we actually measure what the ocean is doing. An amazing reversal is underway now. Whereas in the past we measured temperature, salt, oxygen and other properties from research vessels, we were hard-pressed to give much detail about currents. Today we can measure currents in phenomenal detail, but we can’t measure water properties (from vessels in regular traffic)! The XBT is the only exception. We need to do better, and that was one of (several) reasons for initiating the SCOR working group ‘OceanScope’ – to explore ways of scaling up the activities of working with the merchant marine, and to develop the technologies optimized for that environment.


Ph.D. Oceanography, Massachusett Institute of Technology, 1966 

B.S. Applied Physics, Royal Institute of Technology, Sweden, 1962

Selected Publications

Chafik, L.,  Nilsson, J.,  Rossby, T., &  Kondetharayil Soman, A. (2023).  The Faroe-Shetland Channel Jet: Structure, variability, and driving mechanisms. Journal of Geophysical Research: Oceans,  128, e2022JC019083. https://doi.org/10.1029/2022JC019083

Chafik, L., H. Hátún, J. Kjellsson, K. M. H. Larsen, T. Rossby, and B. Berx, 2020. Discovery of an unrecognized pathway carrying overflow waters toward the Faroe Bank Channel. Nat Comm. 11, 3721 https://doi.org/10.1038/s41467-020-17426-8

Rossby, T., Chafik, L., & Houpert, L., 2020. What can hydrography tell us about the strength of the Nordic Seas MOC over the last 70 to 100 years? Geophys. Res. Lett., 47, e2020GL087456. https://doi.org/10.1029/2020GL087456


Belkin, I., A. Foppert, T. Rossby, S. Fontana, and C. Kincaid, 2020. A double-thermostad warm-core ring of the Gulf Stream. J. Phys. Oc.,50, 489-507 DOI: 10.1175/JPO-D-18-0275.1


Rossby, T., C. Flagg, K. Donohue, S. Fontana, R. Curry, M. Andres, and J. Forsyth, 2019. The Oleander is more than a flower: Twenty-five years of Oceanography aboard a merchant vessel. Oceanography, 32(3), 82-95.


Rudnickas, D., J. Palter, D. Hebert and T. Rossby, 2019. Isopycnal mixing in the North Atlantic Oxygen Minimum Zone revealed by RAFOS floats. J. Geophys. Res. 124(9), 6478-6497 https://doi.org/10.1029/2019JC015148


Chafik, L. and T. Rossby, 2019. Volume, heat and freshwater divergences in the subpolar North Atlantic suggest the Nordic Seas as key to the state of the meridional overturning circulation.  Geophys. Res. Lett., 46, https://doi.org/10.1029/2019GL082110


Rossby, T., C. Flagg, L. Chafik, B. Harden and H. Søiland, 2018. A direct estimate of volume, heat and fresh water exchange across the Greenland-Iceland-Faroe-Scotland Ridge.  J. Geophys. Res. Oceans, 123. https://doi.org/10.1029/2018JC014250


Bosse, A., I. Fer, H. Søiland, and T. Rossby, 2018. Atlantic water transformation along its poleward pathway across the Nordic Seas. J. Geophys. Res, 123. 6428–6448. https://doi.org/10.1029/2018JC014147


Rossby, T., G. Reverdin, L. Chafik, and H. Søiland, 2017. A direct estimate of poleward volume, heat, and freshwater fluxes at 59.5°N between Greenland and Scotland, J. Geophys. Res., 122, doi:10.1002/2017JC012835.


Søiland, H., L. Chafik, and T. Rossby, 2016. On the long-term stability of the Lofoten Basin Eddy. J. Geophys. Res. Oceans, 121, doi:10.1002/ 2016JC011726.


Rossby, T., 2016. Visualizing and quantifying oceanic motion. Ann. Rev. Mar. Sci. 2016. 8:7.1–7.23. 10.1146/annurev-marine-122414-033849


Rossby, T., 2014. On the structure and distribution of thin anti-cyclonic lenses in the southeast Pacific Ocean. J. Mar. Res., 72,383-403.


Søiland, H. and T. Rossby, 2013. On the structure of the Lofoten Basin Eddy. Journal of Geophysical Research, 118, 4201–4212,doi:10.1002/jgrc.20301

OceanScope, 2012. A proposed partnership between the Maritime Industries and the Ocean Observing Community to monitor the Global Ocean Water Column. Final report of SCOR/IAPSO working group 133. Rossby, T. and K. Kim, co-chairs. SCOR/IAPSO March 1, 2012

Rossby, C. Flagg, P. Ortner, and C. Hu, 2011. A Tale of Two Eddies: Diagnosing coherent eddies through acoustic remote sensing. Journal of Geophysical Research. 116, C12017, doi:10.1029/2011JC007307

McGrath, G, T. Rossby, and J. Merrill. Drifters in the Gulf Stream, 2010. J. Marine Research, 68, 699-721

Rossby, T., C. Flagg, and K. Donohue, 2010. On the Variability of Gulf Stream Transport from Seasonal to decadal Timescales. J. Marine Research, 68,503-522.

Rossby, T., V. Ozhigin, V. Ivshin, and S. Bacon, 2009. An Isopycnal Analysis of the Nordic Seas Hydrography. Deep Sea Research, 56, 1955-1971.

Rossby, T., M. Prater and H. Søiland, 2009. Pathways of inflow and dispersion of warm waters in the Nordic Seas. J. Geophys Res.. 114, C04011, doi:10.1029/2008JC005073, 2009

Søiland, H., M. Prater, and T. Rossby, 2008. Rigid topographic control of currents in the Nordic Seas. Geophys. Res. Letters, 35, L18607, doi:10.1029/2008GL034846.

Luce, D. and T. Rossby, 2008. On the size and distribution of rings and coherent vortices in the Sargasso Sea, J. Geophys. Res., 113, C05011, doi:10.1029/2007JC004171.

Woityra, W. and T. Rossby, 2008. Current Broadening as a Mechanism for Anticyclogenesis at the Northwest Corner of the North Atlantic Current. Geophys. Res. Letters, 35, L05609, doi:10.1029/2007GL033063

Rossby, T., 2007. “Evolution of Lagrangian methods in Oceanography. Chapter 1 in Lagrangian Analysis and Prediction in Coastal and Ocean Processes. Cambridge University Press.

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