Sea Level Response to Pressure Forcing in a Barotropic Numerical Model

Abstract A barotropic shallow-water model is used to study the large-scale sea level response to realistic barometric forcing at periods ranging from 1 day to 1 year. Results are presented from coarse resolution “open” ocean experiments (i.e., no shallow continental shelf regions or marginal seas) with coastal geometries and bottom topography representative of the North Atlantic and Pacific basins. The validity of the inverted barometer (IB) approximation is examined in detail, including nonlocal effects which result from taking into account the constant volume of the ocean. These effects are found to be important at low latitudes, where a considerable part of the sea level variability is related to pressure forcing over higher latitudes. Root-mean-square deviations from an IB response in the range of 1–3 cm are typical, with most of the variance occurring at high frequencies. Basin-averaged estimates yield IB deviations of only a few percent at time scales longer than 1 week increasing to 5%–20% over the...