Portsmouth Harbor Observatory

In the past year, a team from the Center for Coastal and Ocean Mapping/Joint Hydrographic Center (CCOM/JHC) (Research Engineer Glenn McGillicuddy, Research Professor Lloyd Huff, CCOM Director Larry Mayer, Research Assistant Professor Tom Weber, and graduate students Val Schmidt and Michelle Weirathmueller) has begun the development of a small-scale oceanographic observatory at the entrance to Portsmouth Harbor (between New Castle Island, NH and Kittery Point, ME).  This is an area of particular interest to CCOM researchers because it is frequently used as test bed for commercial hydrographic sensor systems. (full story) 

The initial stages of this project have been focused on developing an underwater acoustic tracking system near the mouth of the harbor that could be used for high precision positioning of underwater vehicles, in-situ seafloor characterization probes, and other in-water sampling systems. 

In January 2007, infrastructure for the initial acoustic tracking node was installed with the aid of the R/V Gulf Challenger, UNH divers Glen Rice and Stanley Boduch, CCOM lab manager Andy Mcleod, and Jackson Estuarine  Lab manager Dave Shay.  This cable-to-shore installation currently consists of a set of four hydrophones, signal conditioning electronics, and a small computer on a submerged mount located approximately 100 m from Portsmouth Harbor Light on New Castle Island.  Power and data communications utilize a multi-conductor underwater cable connecting the submerged hydrophone system with a ‘topside’ computer housed inside the lighthouse.  A wireless Ethernet system provides connectivity with the outside world, enabling the complete system to be controlled from any convenient location (e.g., on a research vessel, in project team member’s offices, or even at the local coffee shop!).

Initial system testing has been focused on determining the useful range for this system by ‘pinging’ at the hydrophones from various locations around the harbor entrance.  Results thus far look promising for ranges up to 1.5 km, even on the shallow west side of the navigation channel.  In the short term, the project team will be focused on determining the overall accuracy of this tracking system.  The longer term goals are still being formed, but could include support for a variety of oceanographic measurements such as the spatial and temporal variations in currents, temperature, salinity, and sound speed.

Michelle Weirathmeueller and Andy Mcleos 'flaking out' underwater cable.