Abstract
A data assimilative ocean circulation model is used to hindcast the interaction between a large Gulf Stream Warm Core Ring (WCR) with the Mid‐Atlantic Bight (MAB) shelf and slope circulation. Using the recently developed Incremental Strong constraint 4D Variational (I4D‐Var) data assimilation algorithm, the model assimilates mapped satellite sea surface height (SSH), sea surface temperature (SST), in situ temperature, and salinity profiles measured by expendable bathythermograph, Argo floats, shipboard CTD casts, and glider transects. Model validations against independent hydrographic data show 60% and 57% error reductions in temperature and salinity, respectively. The WCR significantly changed MAB continental slope and shelf circulation. The mean cross‐shelf transport induced by the WCR is estimated to be 0.28 Sv offshore, balancing the mean along‐shelf transport by the shelfbreak jet. Large heat/salt fluxes with peak values of 8900 W m−2/4 × 10−4 kg m−2 s−1 are found when the WCR was impinging upon the shelfbreak. Vorticity analysis reveals the nonlinear advection term, as well as the residual of joint effect of baroclinicity and bottom relief (JEBAR) and advection of potential vorticity (APV) play important roles in controlling the variability of the eddy vorticity.
Key Points
Large transport was induced by Gulf Stream Warm Core Ring
The nonlinear advection and JEBAR play important roles in eddy dynamics
The Gulf Stream Ring has strong impact on coastal circulation