Turbulent mixing in the seasonally-stratified western Irish Sea: a Thorpe Scale perspective
Other literature type
Stansfield, K. L.
Palmer, M. R.
Rippeth, T. P.
Simpson, J. H.
(issn: 1812-0792, eissn: 1812-0792)
The seasonal thermocline in shelf-seas represents an important
biogeophysical barrier to the vertical flux of nutrients into the
photic zone. Episodic weakening of this barrier plays an important
role in sustaining the sub-surface chlorophyll maximum in summer and
hence impacts the carbon draw-down in the seasonally-stratified
zones of the shelf seas. Here we present estimates of the rate of
turbulent kinetic energy dissipation inferred from microstructure
shear probes and compare them with dissipation rates inferred from
a standard conductivity-temperature-depth instrument and from a fast
thermistor (Thorpe Scale methodology) at a site in the
seasonally-stratified Irish Sea. All methods show strong dissipation
rates in response to tidal stresses near the bed (order
10<sup>−2</sup> Wm<sup>−3</sup>) with qualitatively similar temporal and
spatial patterns. In the interior of the water column, however,
only the microstructure shear probe estimates resolve the mixing in
the region of the thermocline.