Spatiotemporal variations of cross-shelf exchanges in the Gulf of Maine

The hydrodynamic model Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) is configured for the northeast US coast from Long Island Sound to the Gulf of Maine with a variable resolution from 200 m at the coast to 6 km offshore. The model domain extends eastward to include the Gulf of Saint Lawrence at relatively coarser resolutions. We will present model simulations for years from 2014 through 2017, which are validated using in-situ observations and remote sensing data.

We use the model results to investigate cross-shelf exchanges between nearshore waters and two different coastal currents in the Gulf of Maine by releasing passive particles and using PTRACK code in SCHISM to examine how particles move across the shelf between nearshore waters and the coastal currents. While tides interacting with topography determines the patterns of cross-shelf exchange in the eastern Gulf of Maine, river runoffs and winds play significant roles in regulating spatial and temporal variability in the western Gulf of Maine. Overall, we find that cross-shelf exchanges couple with alongshore transport to govern connectivity in the Gulf of Maine and long-distance transport is possible only when particles move in to the coastal currents.