TY - JOUR
T1 - Internal bores and breaking internal tides on the Oregon continental slope
AU - Martini, Kim I.
AU - Alford, Matthew H.
AU - Kunze, Eric
AU - Kelly, Samuel M.
AU - Nash, Jonathan D.
PY - 2013/1
Y1 - 2013/1
N2 - Observations of breaking internal tides on the Oregon continental slope during a 40-day deployment of 5 moorings along 43°12'N are presented. Remotely generated internal tides shoal onto the slope, steepen, break, and form turbulent bores that propagate upslope independently of the internal tide. A high-resolution snapshot of a single bore is captured from lowered acoustic Doppler current profilers (LADCP)/CTD profiles in a 25-h time series at 1200 m. The bore is cold, salty, over 100 m tall, and has a turbulent head where instantaneous dissipation rates are enhanced (∈ > 10-6 Wkg-1) and sediment is resuspended. At the two deepest slope moorings (1452 and 1780 m), similar borelike phenomena are observed in near-bottom high-resolution temperature time series. Mean dissipation rates and diapycnal diffusivities increase by a factor of 2 when bores are present (∈-bores > 10-8 Wkg-1 and Kp-brores > 10-3 ms-1) and observed internal tides are energetic enough to drive these enhanced dissipation rates. Globally, the authors estimate an average of 1.3 kW m-1 of internal tide energy flux is directed onto continental slopes. On the Oregon slope, internal tide fluxes are smaller, suggesting that it is a relatively weak internal tide sink. Mixing associated with the breaking of internal tides is therefore likely to be larger on other continental slopes.
AB - Observations of breaking internal tides on the Oregon continental slope during a 40-day deployment of 5 moorings along 43°12'N are presented. Remotely generated internal tides shoal onto the slope, steepen, break, and form turbulent bores that propagate upslope independently of the internal tide. A high-resolution snapshot of a single bore is captured from lowered acoustic Doppler current profilers (LADCP)/CTD profiles in a 25-h time series at 1200 m. The bore is cold, salty, over 100 m tall, and has a turbulent head where instantaneous dissipation rates are enhanced (∈ > 10-6 Wkg-1) and sediment is resuspended. At the two deepest slope moorings (1452 and 1780 m), similar borelike phenomena are observed in near-bottom high-resolution temperature time series. Mean dissipation rates and diapycnal diffusivities increase by a factor of 2 when bores are present (∈-bores > 10-8 Wkg-1 and Kp-brores > 10-3 ms-1) and observed internal tides are energetic enough to drive these enhanced dissipation rates. Globally, the authors estimate an average of 1.3 kW m-1 of internal tide energy flux is directed onto continental slopes. On the Oregon slope, internal tide fluxes are smaller, suggesting that it is a relatively weak internal tide sink. Mixing associated with the breaking of internal tides is therefore likely to be larger on other continental slopes.
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U2 - 10.1175/JPO-D-12-030.1
DO - 10.1175/JPO-D-12-030.1
M3 - Article
AN - SCOPUS:84874969086
SN - 0022-3670
VL - 43
SP - 120
EP - 139
JO - Journal of Physical Oceanography
JF - Journal of Physical Oceanography
IS - 1
ER -