Forecasting and seasonal variability of the foot of the Shelfbreak Front in the Northern Middle Atlantic Bight

Abstract The Shelfbreak Front in the Northern Middle Atlantic Bight delineates the boundary between colder, fresher shelf water and warmer, saltier slope water. The location of the foot of the Shelfbreak Front, where the frontal isohalines and isopycnals intersect the bottom, is highly dynamic, impacting several commercial fisheries. In this work, we present new indices to quantify seasonal and interannual variability in the movement of the foot of the Shelfbreak Front. One index is generated from over three decades of observational Conductivity, Temperature, and Depth (CTD) data, and the other from GLORYS reanalysis fields. After detrending and removing seasonality, both indices capture similar variability and were found to be statistically significantly correlated with upstream along-shelf geostrophic velocities derived using satellite altimetry data. Using the lag correlation between the along-shelf geostrophic velocities from the Scotian Shelf to Georges Bank, skillful forecasts for the frontal indices were obtained up to three seasons in advance. This work provides a useful methodology for including variability of the foot of the Northern Middle Atlantic Bight Shelfbreak Front into ecosystem and stock assessment models using readily available near-real-time satellite altimetry data.