Tidal and residual currents over abrupt deepsea t

Authors: Christian Mohn Svetlana Erofeeva Robert Turnewitsch Bernd Christiansen Martin White

Publish Date: 2013/01/30

Volume: 63, Issue: 2-3, Pages: 195-208

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Abstract

The response of tidal and residual currents to smallscale morphological differences over abrupt deepsea topography Seine Seamount was estimated for bathymetry grids of different spatial resolution Local barotropic tidal model solutions were obtained for three popular and publicly available bathymetry grids Smith and Sandwell TOPO82 ETOPO1 and GEBCO08 to calculate residual currents from vesselmounted acoustic Doppler current profiler VMADCP measurements Currents from each tidal solution were interpolated to match the VMADCP ensemble times and locations Root mean square RMS differences of tidal and residual current speeds largely follow topographic deviations and were largest for TOPO82based solutions up to 28 cm s−1 in seamount areas shallower than 1000 m Maximum RMS differences of currents obtained from higher resolution bathymetry did not exceed 17 cm s−1 Single depthdependent maximum residual flow speed differences were up to 8 cm s−1 in all cases Seine Seamount is located within a strong mean flow environment and RMS residual current speed differences varied between 5  and 20  of observed peak velocities of the ambient flow Residual flow estimates from shipboard ADCP data might be even more sensitive to the choice of bathymetry grids if barotropic tidal models are used to remove tides over deep oceanic topographic features where the mean flow is weak compared to the magnitude of barotropic tidal or baroclinic currents Realistic topography and associated flow complexity are also important factors for understanding sedimentary and ecological processes driven and maintained by flow–topography interactionWe thank Julia Hummon and Eric Firing University of Hawaii for helpful support of processing VMADCP data using the Common Ocean Data Access System CODASv3 http//currentssoesthawaiiedu/docs/adcp doc/indexhtml We also thank the master and crew of the RSS Discovery The measurements were carried out as part of the EU FP5 project OASIS Contract no EVK3CT200200073OASIS Support of RT through NERC grant NE/G006415/1 is gratefully acknowledged We thank two anonymous reviewers for constructive and helpful comments

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