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Dakar-A (Senegal) Site History

History Summary

Reference Level

Due to the nature of the bottom-mounted pressure gauges, no link could be established between the zero of the gauge values and fixed points on land. Also, tide staff observations or the like were unavailable. This series has no long-term reference level.

Quality Assessment by the UH Sea Level Center

Comments

Although this data set is within the sea level archive, the user must acknowledge that these data represent inferred sea level from a sub-surface pressure gauge, which measures the combined weight of the column of i water and air above it. A constant atmospheric pressure has been subtracted, but variations in atmospheric pressure, which would not be sensed by a conventional float/ well gauge, would affect the measurement of the sub-surface pressure gauge. Techniques of data processing by the originator are discussed in the second reference below.

The depth of the instrument in the water was about 8 m.

The Dakar pressure gauge records consist of four separate segments.

• Dakar-A: 24 December 1982 - 12 December 1983
• Dakar-B: 12 December 1983 - 09 January 1985
• Dakar-C: 30 May 1986 - 16 December 1986
• Dakar-D: 16 December 1986 - 24 May 1989

The series was broken into segments because level jumps could be identified at the time of instrument replacements.

Due to the tendency for pressure gauge sensors to drift, it is beneficial for investigators to know the time span of each instrument deployment (time/date as yyyy/mm/dd/hh(GMT)).

References

Verstraete, J.M., 1988.
Sea level variations in the tropical Atlantic. Time series of ocean measurements, Technical series, UNESCO,4,33-47.

Verstraete, J.M., 1992.
Accuracy of shallow pressure gauges. Joint IAPSO-IOC Workshop on Sea Level Measurements and Quality Control, Paris, 12-13 October, 1992. IOC Workshop Report No. 81, UNESCO. pp. 70-76.