Mass and salt budgets and saline water intrusions for a region of the continental shelf in the southern Mid-Atlantic bight

The Ocean Margins Program (OMP) was conducted across and along the continental shelf to study the mass and salt budgets of shelf water. The temporal means of current meter records indicate that most of the water enters the region in the northern boundary near the shelf break as part of a southward, alongshore current and exits the southeast comer (47% of the net outflux), where there is a strong southeastward seaward flowing current perhaps due to the effects of the isobath squeezing and blocking of Diamond Shoals to the south.; Time series of volume transport (salt flux) across each boundary for both deployments show that the transports (fluxes) across the northern and southern boundaries were highly correlated. The variations of volume transports for the northern and southern boundaries were significantly coherent with the alongshore wind stress and sea level fluctuations. Similar but somewhat lower coherency is shown in the transport across the eastern boundary with them. Cross-spectral and EOF analyses indicate that for deployment 2 the variations of volume transport are also affected at longer (20 day) periods by topographic Rossby waves and/or extension of the Gulf Stream. The volume transport (salt flux) balance within the closed area is well satisfied, with some uncertainty, and the small amount of volume transport (salt flux) fluctuation at the eastern boundary played an important role in adjusting the balance. Time series and their averages of the salt flux and the turbulent salt flux show that turbulent salt fluxes are negligible, and the mean and time-dependent salt fluxes show very similar pattern with the respective mass fluxes because the salt fluxes are almost governed by current velocity fields.; The two OMP mooring deployments revealed the presence of saline water intrusions. Their time scales ranged from 5 to 20 days. These saline water intrusions appear to result from different mechanisms such as the penetration of Gulf Stream water, onshore wind induced Ekman transport, and upwelled bottom boundary layer flow from the slope. The speed of intrusions onto the shelf indicated a flow of 5 to 25 cm/s directed in the cross-shelf direction.