Increasing Frequency of Mid-Depth Salinity Maximum Intrusions in the Middle Atlantic Bight

Shelfbreak exchange processes have been studied extensively in the Middle Atlantic Bight. An important process occurring during stratified conditions is the Salinity Maximum Intrusion. These features are commonly observed at the depth of the seasonal pycnocline, and less frequently at the surface and bottom. Data collected from NOAA's National Marine Fisheries Service Ecosystem Monitoring program as well as data collected from the fishing industry in Rhode Island show that the middepth intrusions are now occurring much more frequently than was reported in a previous climatology of the intrusions (Lentz, 2003, ). The intrusions have a greater salinity difference from ambient water and penetrate large distances shoreward of the shelf break relative to the earlier climatology. The longer term data from the Ecosystem Monitoring program indicates that the increase in frequency occurred in 2000, and thus may be linked to a recent regime shift in the annual formation rate of Warm Core Rings by the Gulf Stream. Given the increased frequency of these salty intrusions, it will be necessary to properly resolve this process in numerical simulations in order to account for salt budgets for the continental shelf and slope.

Automated summary

Shelfbreak exchange processes, particularly the Salinity Maximum Intrusion, have been extensively studied in the Middle Atlantic Bight. Recent data suggests that middepth intrusions are occurring more frequently and with greater salinity difference from ambient water compared to previous studies. The increase in frequency may be linked to a recent regime shift in the annual formation rate of Warm Core Rings by the Gulf Stream. Properly resolving this process in numerical simulations is necessary to account for salt budgets for the continental shelf and slope.