H. Thomas Rossby

TITLE

Emeritus Professor of Oceanography

FIELD

Physical oceanography

AREAS OF EXPERTISE

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

ABOUT/BIO

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.

A native of Sweden, son of a Swedish father and American mother, Rossby 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, 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 is the acoustic Doppler current profiler (ADCP).

“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…” he says.

One of the low-cost techniques he uses is attaching equipment to merchant vessels to record data as they traverse the various shipping lanes, often quite repetitiously. It’s not hard to get the owners of such vessels to go along with the idea “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 located about 1,000m down. At first it was theorized that the meddy originated from the Mediterranean but further studies showed otherwise. Subsequent studies showed that meddies are everywhere 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.”

In semi-retirement, Rossby is modernizing his Stockholm house but he still stays active having taken part in the Ocean Sciences Conference and making plans to give a mini-course in observational oceanography.

EMAIL

trossby@gso.uri.edu

PHONE

(401) 874-6521

OFFICE LOCATION

Watkins 222

WEBSITE

http://po.gso.uri.edu/rafos/index.html

EDUCATION

Ph.D. Oceanography, Massachusetts Institute of Technology 1966
B.S. Applied Physics, Royal Institute of Technology, Sweden 1962

RESEARCH

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.

I have also been a major user of the acoustic Doppler current profiler (ADCP), especially on merchant marine vessels.
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.

TEACHING

Tom Rossby most recently taught an interdisciplinary course titled: ‘A Lagrangian Approach to Oceanography’.

PUBLICATIONS

Chafik, L., T. Rossby and C. Schrum, 2013. On the spatial structure and temporal variability of poleward transport between Scotland and Greenland.. Submitted to Journal of Geophysical Research

Worst, J. S., K. A. Donohue, and T. Rossby, 2013. A comparison of vessel-mounted acoustic Doppler current profiler and satellite altimeter estimates of sea surface height and transports between New Jersey and Bermuda along the CMW Oleander route. Submitted to J. Atmos. Oceanic Tech. In revision

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

Rossby, and C. Flagg. Direct measurement of volume flux in the Faroe-Shetland Channel and over the Iceland-Faroe Ridge. Geophys. Res. Letters, 39, L07602, doi:10.1029/2012GL051269, 2012

OceanScope, 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 Final report, March 1, 2012

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

McGrath, G, T. Rossby, and J. Merrill. Drifters in the Gulf Stream. 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.

Wang, D.-P., C. N. Flagg, K. Donohue, and T. Rossby, 2010. Wavenumber Spectrum in the Gulf Stream from Shipboard ADCP Observations and Comparison with Altimetry Measurements. J. Phys. Oceanogr.,40, doi:10.1175/2009JPO4330.1

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

Rossby, T., M. Prater and H. Søiland. 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. 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.

Fischer, G., D. Lee, M. O’Bara, P. Kasturi, T. Rossby, and C. Recksiek, 2007. Tracking Small Fish with a MW Acoustic Receiver- An Archival Tag Development. IEEE J. Oc. Engineering.

Flagg, C. N., M. Dunn, D. Wang, H. T. Rossby, and R. L. Benway, 2006. A study of the currents of the outer shelf and upper slope from a decade of shipboard ADCP observations in the Middle Atlantic Bight, J. Geophys. Res., 111, C06003, doi:10.1029/2005JC003116.

PRESENTATIONS

“OceanScope” Briefing organized by Dr. Jerry Miller at the White House for senior management at NSF, NOAA and NASA. Friday May 18, 2012

Visualizing and quantifying oceanic motion. Talk at the Ocean Sciences Conference in Salt Lake City, February 2012

Dissecting the structure of ocean currents. Invited talk at the Nordic Marine Sciences Conference, Strömstad, Sweden. Sept 13-16, 2010.

Free falling probe current and temperature measurement system. Proceedings IEEE/CMTC, Charleston, SC. Mar. 17, 2008. With Viola Wolter.

Exchange of waters between the NE Atlantic and Nordic Seas: A Lagrangian Perspective. PO departmental seminar st RSMAS/Univ. Miami Mar 12, 2008.

Lagrangian studies of warmwater pathways in the Nordic Seas. Ocean Sciences meeting Orlando, FL. Mar. 7, 2008. With M. Prater and H. Søiland.

Merchant marine vessels as ocean-level ‘orbiting’ satellites: A science and industry partnership for the systematic observation of the ocean. Invited talk Ocean Sciences meeting Orlando, FL. Mar. 5, 2008.

Zooming in on the ocean with the help of new technologies Or: How Earth’s rotation shapes ocean currents. All high-school talk at the Wheeler School, Providence, Nov 8, 2007.

Sustained ocean observation from merchant marine vessels. Invited lunch talk given at the Ocean Studies Board, National Academies, Washington, Sept 28, 2007.

Isopycnal Analysis of Near-surface Waters in the Norwegian-Barents Sea Region. Conference paper at the Annual Science Conference of the ICES. Maastricht, Sept. 21, 2006. With V. Ozhigin, V. Ivshin and S. Bacon.

The Gulf Stream – A Fundamental Component of our Climate System –A Survey. Invited talk at the Climate Symposium. Reykjavik, Iceland, Sept. 12, 2006.
On the Role of Salt in the Dansgaard-Oeschger Events. Oc. Sci. Meeting, Hawaii. Feb. 23, 2006.