Continuous monitoring systems in long island sound: Description and evaluation

During the past year an instrumentation array consisting of a savonius rotor current meter, water temperature and salinity sensor and a specially designed transmissometer has been in operation on a converted NOMAD buoy deployed in eastern Long Island Sound. This array in combination with meteorological sensors including wind speed and direction, air temperature and barometric pressure is designed to detail aperiodic storm events and to provide quantitative assessments of their effect on suspended material concentrations and mass transport. The systems characteristics and performance during its first year on station is discussed. Reliability and data accuracy is shown to be primarily limited by intense biological fouling during the summer months and mechanical fatigue produced by persistent aperiodic shock loading. To reduce fouling intensity a system using TBTO impregnated leather collars has been developed. Transmissometer window clarity can be maintained for thirty days. Current meter and conductivity probe reliability remain limited to approximately 14 days during periods of maximum fouling. The occurrence of mechanical fatigue has been reduced by redesign and in some cases replacement of the original sensor units. The overall system performance is evaluated with the results being used to establish design criteria for future coastal buoy systems.