| Abstract: | This paper is a brief review of the work carried out by the Proudman Oceanographic Laboratory (POL) in measuring tides and sub-surface pressure variations in the deep water of the ocean basins using Bottom Pressure Recorders (BPRs). It deals particularly with the work of David Cartwright which he began in the early 1970s and carried out until he left POL in 1986 but is continued by his co-workers of that time.The paper mentions the early work in the north Atlantic when instrument deployments were limited to one month duration and describes what was achieved from the measurements. It concentrates mainly on measurements that were made since the early 1980s when it became possible, because of developments in instrument technology, to achieve individual measurements lasting for one year or more. The results obtained from these measurements are described and some interesting features of the spectrum of the pelagic sub-surface pressure are discussed.As instrument technology further improved, it became possible to study low frequency variations in sub-surface pressure. The contributions made by POL to studies of the Atlantic and Indian Oceans and the contribution to ocean circulation studies during the World Ocean Circulation Experiment are discussed. This led to the development of an instrument capable of operating continuously at ocean depths for five years. The preliminary results from a four year deployment of this instrument which was completed in November 1996 are included. |
