|Figure 1. Proposed Low-Cost Acoustic Telemetry System (click for larger image and caption)|
Observations from the coastal ocean are needed in real time for ocean prediction, environmental monitoring and ocean-process studies
Since the 1960's, long-term observations of ocean properties (currents and temperature for example) have been obtained by mooring instruments in the ocean that record data internally.
|Figure 2. Simple Surface Mooring (click for larger image and caption)|
|Figure 3. USCG Boston Approach 'B' Buoy (click for larger image and caption)|
Although now relatively reliable, data from these instruments are not available until the instrument is retrieved (typically 1-6 months), and damage to an instrument or electronic failure is not known until the instrument is recovered. Limited data is being sent from ocean observing systems to shore via satellite and recently, ocean observatories (such as LEO15 offshore of New Jersey), linked to shore via subsea cable, have been established to provide real-time high-resolution observations at a fixed location.
New technologies are now available that have the potential to inexpensively communicate field measurements from many sensors to a user in a few minutes. This technology can fill a niche between internally recording instruments and fixed location, relatively expensive, high data rate observatories. Development of low-cost systems has the potential to provide observations from distributed arrays with multiple sensors on a wide variety of spatial scales.
|Figure 4. Tripod Frame with ADCP (click for larger image and caption)|
|Figure 5. Mooring Locations In Massachusetts Bay (click for larger image and caption)|
Under the National Ocean Partnership Program (NOPP), the Woods Hole Oceanographic Institution and the U.S. Geological Survey, in cooperation with the U.S. Coast Guard, the Massachusetts Water Resources Authority (MWRA), and RD Instruments are developing a low-cost system for retrieving oceanographic data from instruments in the coastal ocean and delivering these data over the World Wide Web.
The conceptual approach is to use low-cost, low-power acoustic transmitters which transmit data from a sensor located on a mooring line or on the bottom in the vicinity of a surface buoy. These individual low-cost transmitters are the key new technology. A relay system on the surface buoy, consisting of an acoustic modem integrated directly with a reliable, medium bandwidth telemetry link, receives the data from the underwater sensor and sends it directly to shore. The system will be demonstrated by transmitting Acoustic Doppler Current Profiler (ADCP) data from two long-term monitoring sites in Massachusetts Bay.
Development of this technology is a cooperative project between the U.S. Geological Survey, the Woods Hole Oceanographic Institution, the U.S. Coast Guard, the Massachusetts Water Resources Authority, and RD Instruments. The work is carried out with funding from the National Ocean Partnership Program and the partners.
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. The use of trade, product, or industry names in this report is for descriptive or location purposes only and does not constitute endorsement of products by the U.S. Government. Opinions and conclusions expressed herein do not necessarily represent those of the USGS.