Oceanography The Official Magazine of
The Oceanography Society
Volume 30 Issue 02

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Volume 30, No. 2
Pages 51 - 52

Observing Internal Tides in High-Risk Regions Using Co-located Ocean Gliders and Moored ADCPs

Rob A. Hall Barbara BerxMark E. Inall
First Paragraph

Internal tides are an important mechanism in the cascade of kinetic energy within the ocean that ranges from large-scale surface tides to small-scale turbulent mixing. Through this cascade, internal tides contribute to the global mixing budget and drive vertical nutrient fluxes that enhance primary productivity in nutrient-limited surface waters. Although internal tides are a common phenomenon over continental shelves and slopes, as they are generated by tidal currents across sloping topography (e.g., shelf breaks, submarine ridges, canyons, and seamounts), directly observing them in these regions can be a challenge because intense commercial fishing activity increases the risk of instrument loss. Internal tide energy flux, an important diagnostic for the study of energy pathways in the ocean, requires repeated full-depth measurements of both potential density and horizontal current velocity over at least a tidal cycle (several weeks to resolve the internal spring-neap cycle). Typically, these measurements are made using an acoustic Doppler current profiler (ADCP) and a string of conductivity-​temperature loggers on a mooring line, or a moored profiler with a CTD and a current meter. These full-depth moorings are vulnerable to being “fished-out” by demersal and pelagic trawling.

Citation

Hall, R.A., B. Berx, and M.E. Inall. 2017. Observing internal tides in high-risk regions using co-located ocean gliders and moored ADCPs. Oceanography 30(2):51–52, https://doi.org/10.5670/oceanog.2017.220.

References

Eriksen, C.C., T.J. Osse, R.D. Light, T. Wen, T.W. Lehman, P.J. Sabin, J.W. Ballard, and A.M. Chiodi. 2001. Seaglider: A long-range autonomous underwater vehicle for oceanographic research. IEEE Journal of Oceanic Engineering 26:424–436, https://doi.org/10.1109/48.972073.

Boettger, D., R. Robertson, and L. Rainville. 2015. Characterizing the semidiurnal internal tide off Tasmania using glider data. Journal of Geophysical Research 120:3,730–3,746, https://doi.org/10.1002/2015JC010711.

Hall, R.A., T. Aslam, and V.A.I. Huvenne. In press. Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider. Deep Sea Research Part I, https://doi.org/10.1016/j.dsr.2017.05.015.

Hall, R.A., J.M. Huthnance, and R.G. Williams. 2011. Internal tides, nonlinear internal wave trains, and mixing in the Faroe-Shetland Channel. Journal of Geophysical Research 116, C03008, https://doi.org/10.1029/2010JC006213.

Hall, R.A., J.M. Huthnance, and R.G. Williams. 2013. Internal wave reflection on shelf slopes with depth-varying stratification. Journal of Physical Oceanography 43:248–258, https://doi.org/10.1175/JPO-D-11-0192.1.

Johnston, T.M.S., D.L. Rudnick, M.H. Alford, A. Pickering, and H.L. Simmons. 2013. Internal tidal energy fluxes in the South China Sea from density and velocity measurements by gliders. Journal of Geophysical Research 118:3,939–3,949, https://doi.org/10.1002/jgrc.20311.

Johnston, T.M.S., D.L. Rudnick, and S.M. Kelly. 2015. Standing internal tides in the Tasman Sea observed by gliders. Journal of Physical Oceanography 45:2,715–2,737, https://doi.org/10.1175/JPO-D-15-0038.1.

Nash, J.D., M.H. Alford, and E. Kunze. 2005. Estimating internal wave energy fluxes in the ocean. Journal of Atmospheric and Oceanic Technology 22:1,551–1,570, https://doi.org/10.1175/JTECH1784.1.

Rainville, L., C.M. Lee, D.L. Rudnick, and K.-C. Yang. 2013. Propagation of internal tides generated near Luzon Strait: Observations from autonomous gliders. Journal of Geophysical Research 118:4,125–4,138, https://doi.org/10.1002/jgrc.20293.