Adminstered through the Maine Sea Grant Program
 

Observations of Tidal, Subtidal and Seasonal variability in Casco Bay Circulation

Casco Bay currently imports more oil than any other port in the Northeast, except New York, and is host to numerous energy and port facilities. Our current understanding of the circulation processes in Casco Bay is limited, especially with respect to the cross-shore exchanges between the inner and out Bay. Observations of long-term currents, temperature and salinity in the Bay's main conduits of exchange are needed to provide information on the major contributions and combined effects of individual forcing mechanisms (e.g. tides, winds, buoyancy inputs) on the tidal, subtidal, and mean circulation during various seasons.

The main goal of this study is to observe the tidal and non-tidal circulation and exchange processes in Casco Bay, with emphasis on the tranpsort and exchange through three main channels separating the interior and outer Bay. Specific ojectives are to:
1)    Measure long-term, continuous time series of current, temperature/salinity at key areas of exchange in Casco Bay;
2)    Characterize the variability of the Western Maine Coastal Current (WMCC) and its interaction with Casco Bay current measurements;
3)    Generate observational data that can be used for comparison with output from trajectory models used by spill responders.

Three acoustic Doppler current profilers (ADCPs) were deployed in March 2004 in three main channels leading into the bay: Portland Channel, Hussey Sound, and Broad Sound (map). In addition, near-surface and near-bottom temperature and salinity sensors were also deployed on the moorings.  Observations will be made for a minimum of 8 months in order to encompass various seasonal conditions. CTD surveys are also being conducted throughout the study to collect climatology data along the boundary separating the Bay and the adjacent shelf.

Agencies and public interst groups charged with protection of marine water quality, fisheries and environmental health will also benefit from this study, as the results will provide information on the flushing between inner and outer Casco Bay, and will elucidate the role of variable seasonal conditions that can affect environmental quality.

Conferences

Year 1 Progress Report

POCO Sighting

Photos (coming)

Updates (15 March 2005)

CTD Sections along the outer Bay Transect (coming)

Portland Head Light in background, UME Portland Channel Buoy
(yellow), and me conducting a CTD profile off the Friends of Casco
Bay RV Bay Keeper, April 2004.

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