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Storms modify baroclinic energy fluxes in a seasonally stratified shelf sea: Inertial‐tidal interaction
Author(s) -
Hopkins Joanne E.,
Stephenson Gordon R.,
Green J. A. M.,
Inall Mark E.,
Palmer Matthew R.
Publication year - 2014
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010011
Subject(s) - baroclinity , energy flux , internal tide , geology , internal wave , mooring , flux (metallurgy) , inertial wave , atmospheric sciences , oceanography , physics , wave propagation , mechanical wave , longitudinal wave , materials science , quantum mechanics , astronomy , metallurgy
Observations made near the Celtic Sea shelf edge are used to investigate the interaction between wind‐generated near‐inertial oscillations and the semidiurnal internal tide. Linear, baroclinic energy fluxes within the near‐inertial ( f ) and semidiurnal (M 2 ) wave bands are calculated from measurements of velocity and density structure at two moorings located 40 km from the internal tidal generation zone. Over the 2 week deployment period, the semidiurnal tide drove 28–48 W m −1 of energy directly on‐shelf. Little spring‐neap variability could be detected. Horizontal near‐inertial energy fluxes were an order of magnitude weaker, but nonlinear interaction between the vertical shear of inertial oscillations and the vertical velocity associated with the semidiurnal internal tide led to a 25–43% increase in positive on‐shelf energy flux. The phase relationship between f and M 2 determines whether this nonlinear interaction enhances or dampens the linear tidal component of the flux, and introduces a 2 day counter‐clockwise beating to the energy transport. Two very clear contrasting regimes of (a) tidally and (b) inertially driven shear and energy flux are captured in the observations.