Estimates of the temperature flux-temperature gradient relation above a sea floor
Cimatoribus, A.; van Haren, H. (2016). Estimates of the temperature flux-temperature gradient relation above a sea floor. J. Fluid Mech. 793: 504- 523. dx.doi.org/10.1017/jfm.2016.112
In: Journal of Fluid Mechanics. Cambridge University Press: London. ISSN 0022-1120; e-ISSN 1469-7645, more
The relation between the ux of temperature (or buoyancy), the verti-cal temperature gradient and the height above the bottom, is investigatedin an oceanographic context, using high-resolution temperature measure-ments. The model for the evolution of a strati?ed layer by Balmforthet al. (1998) is reviewed and adapted to the case of a turbulent owabove a wall. Model predictions are compared to the average observa-tional estimates of the ux, exploiting a ux estimation method proposedby Winters & D'Asaro (1996). This estimation method enables the dis-entanglement of the dependence of the average ux on the height abovethe bottom and on the background temperature gradient. The classicalN-shaped ux-gradient relation is found in the observations. Model andobservations show similar qualitative behaviour, despite the strong sim-pli?cations used in the model. The results shed light on the modulationof the temperature ux by the presence of the boundary, and support theidea of a turbulent ux following a mixing-length argument in a strati?edow. Furthermore, the results support the use of Thorpe scales close to aboundary, if su?cient averaging is performed, suggesting that the Thorpescales are a?ected by the boundary in a similar way as the mixing length.
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