Abstract
Abstract A brief description is given of a Grumman-designed oceanographic instrument that was used to obtain vertical profiles of temperature, salinity, and current speed and direction in a year-long oceanographic study of an area of the New York Bight. The variable buoyancy device that controls the instrumented package, the mooring system, and the computer programs that are used to reduce the data are discussed. Some typical data illustrate the Potential of the device. Introduction During the period October 1973 to November 1974 Grumman Ecosystems Corporation performed an oceanographic survey for the New York Atomic and Space Development Authority in an 800 square mile section off the south shore of Long Island, shown in Fig. 1. The data obtained, included vertical profiles of, current, temperature and salinity collected using Grumman profilers. These instruments were left unattended at moorings for periods ranging from one week to one month collecting data at one and five minute intervals respectively. The profilers move up and down a taut mooring line controlled by a pneumatic variable buoyancy device (VBD). This device and a recording instrument package are enclosed in a streamlined hull. A description of the YED, the profiler and the recording package along with examples of data are presented in the following sections. Variable Buoyancy Device The VBD consists of an aluminum scuba tank, pressure regulator, differential pressure valve, a deep and a shallow valve and a bladder assembly. The tank containing helium is a standard aluminum scuba tank with a capacity of 12 liters and storage pressure of 174 kg/cm2. Not only is this tank lightweight and corrosion resistant but it is also non-magnetic and will not interfere with the compass readings. The regulator valve is a standard DACOR model 200 scuba valve of chrome plated brass which is antimagnetic and corrosion resistant. Since the design output pressure is higher than necessary to inflate the bladder the reference spring in this valve has been placed by a weaker spring. The valve bodies are manufactured from Lexan, a clear plastic, which is much more economical to use than stainless steel. It can be easily machined and is noncorrosive. The use of transparent valves is also convenient when troubleshooting during bench tests. These valves are adjusted by means of stainless steel pressure caps, with the number of turns marked on their sides. By means of a calibration curve selected shallow and deep water depths defining the extent of travel of the profiler can be set by the indicated number of turns. This system was originally designed for deep water operation but in this case was operated in relatively shallow water depths up to 30 meters. As a consequence very fine adjustment of the valves was necessary, as any error or malfunction of the valve could result in travel depth errors which are a considerable fraction of the actual depth.
Published Version
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