ON NONLINEAR EKMAN SURFACE-LAYER PUMPING

Simple expressions are presented for the corrections to the classic Ek man pumping law W-e = (z) over cap . curl(tau(0)/f) due to nonlinear a dvection effects in the surface boundary layer. These involve products of the surface Reynolds stress tau(0) and the underlying ocean curren ts v(0)(x, y, t) and their derivatives, and products of tau(0),(x, y, t) and its own derivatives. The former interaction is independent of t he turbulence closure, while the latter is obtained using solutions fo r a constant eddy viscosity. The corrections are usually small, as is assumed when the linear Ekman pumping relation is applied in ocean mod eling. However, they can become significant in circumstances involving very high wind stresses (e.g., a hurricane), or in situations where a strong narrow oceanic current flows under a region of moderate but pe rhaps relatively uniform surface stress.