The spatial and temporal distribution of the Maine Coastal Current during 1982

The mean position of the cold, less-saline Maine Coastal Current and its spatial and temporal variability in the northern Gulf of Maine during 1982 were studied using optimally interpolated, satellite-derived, sea surface temperature maps and ship of opportunity data. Five-day averaged sea surface temperature maps were produced at five-day intervals at a spatial resolution of ∼11 km from daily, spatially averaged, full-resolution, declouded Advanced Very High Resolution Radiometer data collected over the entire Gulf of Maine. Optimally interpolated mean sea surface temperature errors were less than half of the non-seasonal sea surface temperature root mean square variability over ∼95% of the study domain, including the Maine Coastal Current region. Results showed that 82% (88%) of the non-seasonal sea surface temperature variance within an inshore (offshore) branch of the Maine Coastal Current occurred on time scales of 1–2 months with little variance occurring within the 10-day to 1-month band. Furthermore, the non-seasonal sea surface temperature fluctuations within both branches of the Maine Coastal Current were coherent within the lower frequency band. Sea surface temperatures and ship of opportunity data suggest that the non-seasonal physical, chemical and biological variability within the inshore and offshore branches of the Maine Coastal Current during 1982 are related and were caused by advection resulting from low-frequency variability in the geostrophic flow over Jordan Basin, and exclusive of salinity, may account for most of the observed low-frequency physical, chemical and biological variability measured within the surface and near-surface waters of both branches of the Current during 1982. Differences between the non-seasonal fluctuations of surface salinity measured within both branches of the Maine Coastal Current during 1982 may have resulted from additional forcing by both remote and local freshwater sources.