Summary for Field Activity Number 84024

Alternate Leg ID: OC159

Area of Operations: southern New England shelf and slope, Massachusetts, United States, North America, North Atlantic

Dates: November 13, 1984 to November 20, 1984

Chief scientist: Brad Butman
   

Objectives: This cruise was part of a study of currents and sediment transport on the Continental Slope. Major objectives were: 1) to recover an array of current meters and bottom instruments deployed on the Continental Slope in March 1984 (Slope Array III); 2) to conduct a hydrographic survey across the outer shelf and upper slope between 68 and 71 degrees W. OC159 was the third and last cruise associated with the long-term slope measurements.

Type of Activity: Mooring work

Information to be derived: Time series data
Samples and Chemical Analysis

Summary: Moorings recovered: 7 (#277, 278, 279, 280, 281, and 282 all deployed FA 84004 OCEANUS 149 Mar. 12-19, 1984; #283 deployed FA 84031 OCEANUS 154 May 16-23, 1984). OC159 was the last in a series of 3 cruises conducted as part of a USGS program to study currents and sediment transport on the Continental Slope. The program is supported by the USGS and by the Minerals Management Service. Despite the weather, all major scientific objectives were accomplished. All moorings were recovered and a moderate CTD survey was completed. One section was repeated 3 times during the cruise which should illustrate temporal changes in suspended sediment during typical storm conditions. A 1-m Sea Tech transmissometer was used to make suspended sediment observations. The oxygen sensor on the CTD failed early in the cruise. Two moorings did not surface although both releases indicated that the release mechanism functioned. Both moorings were recovered by dragging. The mooring at SE was jarred free. The mooring at SA was cut above the lower current meter and release. Close inspection of the release recovered at station SE suggests that crevice corrosion in the release pin may have held the mechanism closed. 15 of 16 current meters and 1 tripod were recovered. CTD stations: 41; XBT stations: 3; Salinity samples: 65; Suspended sediment samples: 54; Nutrient samples: 24.

USGS Project Number:

Contact: Brad Butman (bbutman@usgs.gov)

InfoBank: uses the identifier O-59-84-NE. Visit this site for more information.