Description of the HRP and how it is typically used at sea

The High Resolution Profiler (HRP- (shown above, viewed from the top)) was designed and fabricated at the Woods Hole Oceanographic Institution in the mid 1980's. The concept of building an instrument equipped especially for exploring the deep ocean, came from Ray Schmitt and John Toole. Engineers Dick Koehler, Ken Doherty, and Ed Mellinger made the concept a reality. The HRP has been used in eight large experimental programs- a time history shows the development and testing phase, as well as when the experiments and major changes to the instrument occurred.

The photo at the left shows the sensors mounted at the bottom end of the HRP. A description of the HRP, its components and its sensors provides details about the instrument and how it works. A schematic of the sensors and their placement in the hood is also in the description.

A typical HRP dive follows a sequence like the one shown in these pictures- a more complete verbal description follows.

• The HRP is prepared for deployment: the computer inside the instrument is programmed with the dive control parameters, weights are loaded, mechanical systems checks are completed, and the ship is positioned at the desired deployment position.
• The data logging software is started and then the communications cable is disconnected.
• The HRP is deployed (figure by J.Cook).
• The HRP is tracked acoustically during its descent and ascent. When one of several criteria for dive termination is met, data logging is terminated, the descent weights are jettisoned, and the HRP returns to the surface. To assist in tracking, the HRP transducer pings every 20 seconds on the descent, once per second while the weights are being released, and every 5 seconds on its ascent.
• The ship is positioned for recovery a half mile or less from the deployment position to facilitate sighting the HRP when it surfaces.
• The HRP is recovered by the ship. Lines are attached to the profiler using long poles with hooks at the ends, as the ship steams slowly by. Then the HRP is brought on deck using a specialized hydraulic lifting rig.
• The data stored in the HRP is downloaded to a computer on the ship, where the analysis and display of the data occurs. A whole suite of specialized programs exists to process the data acquired by the HRP.
• As the ship steams to the next station, the instrument is readied for another deployment.

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