Long-term observations of bottom current and bottom sediment movement on the mid-Atlantic continental shelf

Journal of Geophysical Research: Oceans
By: , and 

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Abstract

Long-term in situ observations made at three locations on the mid-Atlantic continental shelf during 1975–1976 clearly show intermittent movement of bottom sediment caused by currents, waves, and other forcing mechanisms. In winter, storm-associated bottom currents greater than 30 cm s−1 resuspended and transported sediments. Net water particle excursions during storms were about 20–30 km longshelf and 5–10 km cross-shelf. Wave-induced bottom currents also resuspended sediments during periods of low mean flow. Sediment motion was observed in summer, although bottom conditions were generally tranquil. Significant changes in suspended matter concentration were observed that were only partially related to bottom currents. These changes may have been caused by biological activity or advection. Bottom currents on the mid-Atlantic region of the continental shelf were characterized by a coherent, primarily cross-shelf tidal flow of 5–10 cm s−1 and a low-frequency longshelf component of 5–20 cm s−1. The longshelf current was coherent over length scales of 100 km at tidal frequencies and for motions with periods greater than 50 hours. For these longer periods the longshelf flow was coherent with wind stress, which implies that winds were a major driving force of the longshelf current. The cross-shelf current was not coherent at stations separated by 100 km except at tidal frequencies. Packets of high-frequency internal waves were observed during stratified conditions in summer with bottom currents as large as 20 cm s−1.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Long-term observations of bottom current and bottom sediment movement on the mid-Atlantic continental shelf
Series title Journal of Geophysical Research: Oceans
DOI 10.1029/JC084iC03p01187
Volume 84
Issue C3
Year Published 1979
Language English
Publisher American Geophysical Union
Contributing office(s) Woods Hole Coastal and Marine Science Center
Description 19 p.
First page 1187
Last page 1205
Country United States
Other Geospatial Mid-Atlantic continental shelf
Online Only (Y/N) N
Additional Online Files (Y/N) N