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Large internal waves in Massachusetts Bay transport sediments offshore

Continental Shelf Research

By:
, , , ,
DOI: 10.1016/j.csr.2006.07.022

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Abstract

A field experiment was carried out in Massachusetts Bay in August 1998 to assess the role of large-amplitude internal waves (LIWs) in resuspending bottom sediments. The field experiment consisted of a four-element moored array extending from just west of Stellwagen Bank (90-m water depth) across Stellwagen Basin (85- and 50-m water depth) to the coast (24-m water depth). The LIWs were observed in packets of 5–10 waves, had periods of 5–10 min and wavelengths of 200–400 m, and caused downward excursions of the thermocline of as much as 30 m. At the 85-m site, the current measured 1 m above bottom (mab) typically increased from near 0 to 0.2 m/s offshore in a few minutes upon arrival of the LIWs. At the 50-m site, the near-bottom offshore flow measured 6 mab increased from about 0.1 to 0.4–0.6 m/s upon arrival of the LIWs and remained offshore in the bottom layer for 1–2 h. The near-bottom currents associated with the LIWs, in concert with the tidal currents, were directed offshore and sufficient to resuspend the bottom sediments at both the 50- and 85-m sites. When LIWs are present, they may resuspend sediments for as long as 5 hours each tidal cycle as they travel westward across Stellwagen Basin. At 85-m water depth, resuspension associated with LIWs is estimated to occur for about 0.4 days each summer, about the same amount of time as caused by surface waves.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Large internal waves in Massachusetts Bay transport sediments offshore
Series title:
Continental Shelf Research
DOI:
10.1016/j.csr.2006.07.022
Volume
26
Issue:
17-18
Year Published:
2006
Language:
English
Publisher:
Elsevier
Contributing office(s):
Coastal and Marine Geology Program
Description:
21 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2029
Last page:
2049
Number of Pages:
21
Country:
United States
State:
Massachusetts
Other Geospatial:
Massachusetts Bay