Research interests:

My research interests, past and present, can be broadly split into three categories. Observing the Ocean using Sound, Small-scale Biophysical Interactions and Straits and Fjords.


Observing the Ocean using Sound

Acoustics opens a window revealing an underwater world. Light cannot reach the oceans' depths, so often the only way to "see" something at a distance is through the observation of reflected sound waves rather than light

waves. For nearly three quarters of a century oceanographers have used sonar technology to learn about the ocean interior. This powerful tool does, however, have some limitations. Using standard narrowband sonar it is difficult to distinguish between different sources of scatter. This makes it tricky to apply quantitative data analysis to determine concentrations of fish or plankton, or the amount of mixing between interacting ocean currents. This is where we come in.


Acoustic colour

One problem is that we have been limiting ourselves by "viewing" the ocean in black and white. Traditional narrowband sonar uses a single acoustic frequency. This is like viewing the world in only one colour, since colour is defined by the frequencies of light that are preferentially reflected by an object. Restricting our eyes to observing only one frequency of light is like observing the world in black and white. Clearly, we have a much easier time identifying objects when we see them in full colour.


My lab works on developing acoustic colour techniques for the ocean. Broadband sonar allows the observation of a wider frequency spectrum of acoustic scattering. We develop and apply broadband acoustic methods, in both the laboratory and the field, to extract information on plankton size and variability of fluid properties from spectral data.


Moving towards acoustic remote sensing of ocean turbulence
The basic fluid mechanics controlling acoustic scattering from turbulent microstructure is that the turbulent motions act on the ambient gradients in sound speed and density (prescribed by temperature and salinity gradients in the ocean) to create fluctuations in sound speed and density on many scales. When the incident acoustic wave encounters a parcel of water the size of its wavelength, with a different sound speed or density, it is scattered (either through an isotropic compression or a dipole-like inertial oscillation).

While the physics leading to sound scattering from turbulence is relatively easy to understand, we are still a long way from using acoustics to routinely remotely sense turbulence and mixing in the ocean. My work uses a combination of field and laboratory experiments to further our understanding of the relative new field of acoustic scattering from turbulence and turn it into a practical tool for oceanographers.


Mapping double-diffusive convection in polar regions

Polar regions, with their supercooled and relatively fresh surface water, are highly susceptible to the diffusive regime of double-diffusive convection (DDDC). Whether the fluxes associated with the DDDC play a significant role in the heat/buoyancy budgets in polar regions is an open question. We’re working on a high-frequency acoustic technique that can be used to quickly map the extent and evolution of the DDDC. Further, broadband acoustics offers a rapid and remote method to infer fluxes, without the need for time-consuming microstructure measurements, suggesting that this technique will be a boon to field studies of DDDC.


Small-scale Biophysical Interactions

This is a relatively new area of study for me. I am interested in all different types of small-scale biophysical interactions, from the formation of thin layers to larval retention in coral reefs to the behaviour of zooplankton under different turbulent and non-turbulent flow conditions. I have been doing laboratory work for several years and have recently started observing the real ocean.


Does turbulence affect zooplankton behaviour?

This is a key interest of mine. I’ve just had a new type of profiler--a video plankton and microstructure profiler, to be precise--built to study plankton in turbulence in the ocean. The data have just started to come in. Stay tuned for results.


Straits and Fjords

This is something I haven’t been active in for a while. I studied inter-annual variations in the exchange flow through the Strait of Gibraltar using tide-gauge and satellite altimetry data.

Tetjana Ross

Associate Professor
Department of Oceanography

College of Sustainability (cross-appointed)
Dalhousie University
Halifax, NS B3H 4R2, Canada
Tel: 902.494.1327

Fax: 902.494.2885
Office: LSC 5672

e-mail: tetjana@dal.ca


CV


Current Teaching

  1. Conversations with Ocean Scientists

  2. Environment, Sustainability and Society Honours (co-instructor)

  3. Introduction to Environment, Sustainability and Society 1 (Guest)

  4. Humanity in the Natural World: An Introduction to Problem Based Learning (Guest)

Recent Teaching

  1. Special Topics in Oceanography

  2. Introduction to Environment, Sustainability and Society 2 (Guest)

  3. Environment, Sustainability and Society Capstone (Guest)

  4. Fluid Dynamics I


Prospective Students

I am always seeking strong students interested in acoustical and biophysical oceanography. Please contact me if interested.


Current Lab


Nick Dourado

MSc Student


Dylan DeGrace

MSc Student


Lab Alumni

Candace Smith MSc

Doris Leong MSc

Kirk Herman Undergrad (Co-op)

Robbie Paterson Undergrad (Co-op) Amy Roy Undergrad (Honours)

Ed Marchant Undergrad (Honours)

Beth MacEachern Undergrad (Co-op)

Ivan Kostylev Undergrad (Co-op)

Andria Roy Undergrad (Honours)

Caitlin Gerber Undergrad (Co-op)

Keir Colbo Research Associate


Recent Publications

Ross, T., J. E. Keister, and A. Lara-Lopez, 2013. On the use of high-frequency broadband sonar to classify biological scattering layers from a cabled observatory in Saanich Inlet, British Columbia. Meth. Oceanog., 5:19-38, doi:10.1016/j.mio.2013.05.001.


Davies, K., T. Ross, and C. Taggart, 2013. Tidal and sub-tidal currents influence deep copepod aggregations along a shelf-basin margin. Mar. Ecol. Prog. Ser., 479:263-282, doi: 10.3354/meps10189.


Leong, D., T. Ross, and A. Lavery, 2012. Anisotropy in high-frequency broadband acoustic backscattering in the presence of turbulent microstructure and zooplankton. J. Acoust. Soc. Am. 132:670-679, doi: 10.1121/1.4730904.


Roy, A., A. Mextaxas and T. Ross, 2012. Swimming patterns of larval Strongylocentrotus droebachiensis in turbulence in the laboratory. J. Exp. Mar. Biol. Ecol. 453:117-127,  doi:10.3354/meps09662


Ross, T.  and A. Lavery, 2012. Acoustic scattering from density and sound speed gradients: Modeling of oceanic pycnoclines. J. Acoust. Soc. Am. 131:EL54-EL60, doi: 10.1121/1.3669394.


Ross, T.  and A. Lavery, 2010. Acoustic detection of oceanic double-diffusive convection: A

feasibility study. J. Atmos. Oceanic Technol. 27:580–593, doi: 10.1175/2009JTECHO696.1.


Sameoto, J., T. Ross  and A. Metaxas, 2010. The effect of flow on larval vertical distribution of the sea urchin, Strongylocentrotus

droebachiensis. J. Exp. Mar. Biol. Ecol. 383:156-163, doi:10.1016/j.jembe.2009.11.014 .


Ross, T.  and A. Lavery, 2009. Laboratory observations of double-diffusive convection using high-frequency broadband acoustics. Exp. Fluids, doi:10.1007/s00348-008-0570-9.


Lavery, A. and T. Ross, 2007. Acoustic scattering from double-diffusive microstructure. J. Acoust. Soc. Am., 122(3), 1449-1462. doi: 10.1121/1.2764475.


Ross, T., I. Gaboury and R. Lueck, 2007. Simultaneous acoustic observations of turbulence and zooplankton in the ocean, Deep Sea Res., 54, 143-153, doi:10.1016/j.dsr.2006.09.009.


Ross T. and R. Lueck, 2005. Estimating turbulent dissipation rates from acoustic backscatter, Deep Sea Res., 52(12), 2353-2365, doi:10.1016/j.dsr.2005.07.002.

Thesis
Ross T., 2003.
Sound scattering from oceanic turbulence, Ph.D. Thesis, University of Victoria.

Other interests

  1. Untamed Interiors

  2. Jeff’s photography