ON THE ESTABLISHMENT OF THE SEASONAL PYCNOCLINE IN THE MIDDLE ATLANTIC BIGHT

Each year the hydrography of the Middle Atlantic Bight changes dramati cally from winter conditions with strong horizontal gradients of tempe rature, salinity, and density at the shelf break separating shelf and slope waters to the summer stratification with a sharp pycnocline at a bout 20-m depth across both the shelf and slope and weak horizontal de nsity gradients. We use a simple one-dimensional diffusion model to de monstrate that this change could result from a uniform surface heating provided that the nonlinearity of the equation of state is taken into account.