Development of a multi-year deep sea bottom pressure recorder

A new deep ocean instrument has been developed by the Technology Group of the Proudman Oceanographic Laboratory. MYRTLE (Multi-Year Return Tidal Level Equipment) is a self-contained instrument for long term deployment on the sea bed. It is capable of making continuous measurements of sea pressure and temperature using high precision quartz crystal sensors. The measured data are transferred to solid state memory contained in several buoyant, releasable data capsules (RDC) which provide a means for data retrieval. The capsules can either be recovered on the surface following an acoustic command to a release or can be pre-programmed to release at yearly intervals and relay the data from the sea surface through a satellite telemetry link, thereby avoiding the expense of a recovery ship. Where applicable, well-proven instrumental techniques have been used in the system to ensure reliability. Several new technologies have been applied in the data formatting and storage systems. A novel method of data transfer to the RDC has been employed using infra-red emitters and receivers communicating through the sea-water/glass interface.