Predicting Internal Solitary Waves in the Gulf of Maine

Abstract

Internal solitary waves (ISWs) are important physical processes in the Gulf of Maine (GoM), which is one of the most productive ecosystems of the Northwest Atlantic. In order to understand the roles that ISWs play, it is necessary to have synthesized knowledge of their timing and distributions. We detail the ISW spatial distribution patterns in the GoM using modern high-resolution satellite imagery. A prediction methodology is suggested based on the speed of mode-1 ISWs, which is cross validated using three methods: Remote sensing based on positional displacements of ISWs strips in continuous images, theoretical analysis based on climatological ocean stratification, and an empirical method based on bathymetry. Prediction accuracy is further validated by independently collected high spatial resolution satellite images from multiple sensors. We found a new-generation site for ISWs near Grand Manan, with wave crests extending over the entire GoM. Interference of ISWs originating from the new-generation site and the well-known generation location on Georges Bank, plus local-scale ISW generation sites, creates cross-sea conditions within the water column, resulting in complex ISWs. We find that the background barotropic currents do not significantly influence the ISW spatial distributions, which simplifies the prediction of ISWs; we also consider the influence of tidal currents, general circulation, and stratification. This methodology is potentially useful for additional studies, for example, linking ISWs, energy and nutrient budgets, mixing, and primary production in the Gulf of Maine.