A Numerical Investigation of the Interannual-to-Decadal Variability of the Along-shelf Transport in the Middle Atlantic Bight

A numerical simulation with the Regional Ocean Modeling System (ROMS) indicates that there is significant interannual-to-decadal variability of along-shelf transport and water properties over the Middle Atlantic Bight (MAB) from 2004-2013. To examine the relative contribution from local atmospheric forcing versus remote oceanic open boundary forcing to such low-frequency variability, we implement a suite of process oriented numerical experiments. Results show that the interannual variability is dominated by remote forcing from the open boundaries of the region rather than by the local forcing from the atmosphere. The penetration of the Labrador Current into the region contributes to a significant increase of along-shelf transport in the winters of 2009 and 2010. By contrast, the anticyclonic mesoscale eddies associated with Gulf Stream have negative impacts on the along-shelf jet, and in certain cases, even reverse the along-shelf transport. In addition, the along-shelf transport appears to have a decadal transition, i.e., weaker during 2004-2008 but stronger during 2009-2013.