Science Mission 5

Spatial variability of bottom turbulence over a sandbank

Theoretical work on the development and maintenance of sandbanks, using existing data on peak tidal flows over the sandbanks of the southern North Sea, has suggested that the bottom stress expected in the troughs between the banks is in the order of 1 N m^-2 and that these values increase by a factor of order 2 over the crest of the banks.

Why use Autosub?

The development of Autosub provided a unique opportunity for the spatial mapping of flow and turbulence over uneven topography such as that encountered over ridges. Whereas previous measurements were either limited to single points or averaged over the entire wavelength of the shoals, Autosub collected sufficient data to enable the enhancement of models which accurately predict the development and maintenance of sandbanks.

Related publications

Voulgaris G., Trowbridge J.H. and Terray E., 2002. AUV-Based Flow and Turbulence Gradient Measurements: The Wish of a Modeller. EOS Transactions, American Geophysical Union, 83(4) Ocean Sciences Meeting Supplement.

Fornwalt B., Terray E., Voulgaris G. and Trowbridge J.H., 2002. Flow Modelling around an Autonomous Underwater Vehicle with Applications to Turbulence Measurements. EOS Transactions, American Geophysical Union, 83(4) Ocean Sciences Meeting Supplement.