AUTHOR=van Haren Hans , Duineveld Gerard , Mienis Furu 

TITLE=Internal Wave Observations Off Saba Bank

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 5 - 2018

YEAR=2019

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2018.00528

DOI=10.3389/fmars.2018.00528

ISSN=2296-7745

ABSTRACT=The deep sloping sides of Saba Bank, the largest submarine atoll in the Atlantic Ocean, show quite different internal wave characteristics. With the aid of two 350 m long arrays of high-resolution temperature T-sensor string and acoustic Doppler current profiler that were moored around 500 m depth for three weeks we observed that the surrounding waters were generally stratified in density layers of multiple sizes, that turbulence is about a factor of two less than the strong turbulence previously observed above comparable steep slopes above Atlantic seamounts and that near-bottom nonlinear turbulent bores are absent. Both the Banks’ north-side and south-side slopes are locally steeper than internal tide slope angles. However, the three times weaker north-side slope shows quasi-mode-2 semidiurnal internal tides over the range of observations, centered with dominant near-inertial shear around 150 m above the bottom, but generating the largest turbulence when touching the bottom and showing off-bank flowing turbid waters. In contrast, the steeper south-side slope shows quasi-mode-1 internal tides having occasionally excursions >100 m crest-trough, with weak inertial shear and smallest buoyancy scale turbulence periodicity occurring near the bottom and about half-way the water column, below abundant coral reefs in shallow <20 m deep waters. A -5/3 inertial subrange is found within the internal wave band at frequencies below the buoyancy frequency.