Other ID: STRL S5-87-AFR
Organization(s): USGS, Woods Hole Coastal and Marine Science Center
Principal Investigator(s): Barry Irwin
Data Type(s): Electro-Magnetic: Gravity, Sonar: Single Beam, Electro-Magnetic: Magnetics, Location-Elevation: Navigation
Scientific Purpose/Goals: Collect gravity, magnetics and bathymetric data around Senegal, Gambia, Guinea-Bissau, Guinea, and Sierra Leone to a 3 nm grid with internal consistency +/-3 mgals.
Start Port/Location: Dakar, Senegal
End Port/Location: Freetown, Sierra Leone
Start Date: 1987-07-22
End Date: 1987-08-20
Equipment Used: LaCoste-Romberg gravimeter G-179, 12 kHz, Geometrics G-856 magnetometer, GE 810 Correlation sonar, Gyro compass, GPS (wh), Magnavox satellite positioning system
Information to be Derived:
Summary of Activity and Data Gathered: Departed Dakar at 1920 on 22 Jul. 1987. The ship proceeded south to survops area. After completing the two remaining lines in Senegal, all runable lines in the waters off The Gambia, Guinea-Bissau, Guinea and Sierra Leone were completed. Most of the onshore lines run north of Sierra Leone were shortened due to shoals on the eastern ends. Gravimeter S-26 lost its 200 Hz power supply on 2 Aug. 87. The unit was swapped with the unit in meter S-41, which was then shut down. S-26 remained online for the remainder of the cruise and showed no evidence of data tears. Arrived in Freetown, Sierra Leone at 1230 on 20 Aug. 1987.
Staff: Barry Irwin, Carol A. Ryland, Sarah Griscom
Robin Bouse; Fernandes Caetano and Batiga Mitchel - Guinea Bissau
Notes: Original Center People field contained: Barry Irwin - party chief, Robin Bouse, Sarah Griscom, Carol Renaud.
Project = Defense Mapping Agency Gravity, Defense Mapping Agency Gravity
Senegal, Gambia, Guinea-Bissau, Guinea, Sierra Leone, Africa, North Atlantic;
|North: 12.5||South: 6.5||West: -17.75||East: -11.5|
Folger, D.W., McCullough, James R., Irwin, Barry J., Driscoll, George R., and Polloni, Christopher F., 1990, Map showing free-air gravity anomalies off the western coast of Africa; Senegal (south of 15 degrees north latitude) to Sierra Leone: , download PDF.
|Survey Equipment||Survey Info||Data Type(s)||Data Collected|
|LaCoste-Romberg gravimeter G-179||---||Gravity|
|12 kHz||---||Single Beam||1987-029-FA-SE-001 ( Collection of paper record displays of seismic data (12 kHz) for lines )|
|Geometrics G-856 magnetometer||---||Magnetics|
|GE 810 Correlation sonar||---||Navigation|
|Magnavox satellite positioning system||---||Navigation|