Buoyancy inputs from riverine discharges form an estuarine-like frontal
zone along coasts. The gravitational component of across-shelf circulation
drives a near-surface flow seaward and a near-bottom flow shoreward.  Using
data from the southeastern U.S. continental shelf, the buoyancy field is
examined under upwelling and downwelling favorable wind stress. Numerical
simulations and field data show that prolonged upwelling-favorable winds
reinforce the gravitational circulation by enhancing its offshore component.
Larger-than-normal riverine discharges in 1993 showed that this
reinforcement caused a lens of warm, low-salinity coastal water to become
detached from the coastal front and be advected seaward.  Reinforcement of
this process enhances the loss of estuarine discharges from coastal areas. 
Climatological data show that this loss increases as the mean upwelling
favorable wind stress for the year increases.