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Abstract:
Ocean turbulence consists of chaotic and intermittent motions that enhance ocean mixing over length-scales ranging from millimeters to hundred kilometers. Intermittency of small-scale turbulent mixing (millimeters-meters scale) is confirmed by observations. For mesoscale velocity statistics that are fundamental to mesoscale mixing (10-100 km), weak intermittency is also observed.However, for mesoscale turbulent mixing itself, intermittency has been less explored. Here we show observational based indications of extreme intermittency of mesoscale ocean mixing.We apply a well-established mesoscale mixing parameterization to moored observations of temperature, salinity, pressure, and velocity in the Irminger Sea. The resulting four-year time series of weekly-mean mesoscale mixing reveals that a few episodic events are responsible for a large fraction of the mixing at this location, and that the observed intermittency affects both the instantaneous and time-mean heat fluxes. These observations suggest the need to further understand and study intermittency of mesoscale mixing in order to account for these effects in their parameterizations.
