Sea Level Forecasts with an EOF Model

Abstract

The theory of empirical orthogonal functions was first applied to sea level forecasting by Holmström and Stokes (1978) and Törnevik (1977), who constructed models for the Baltic Sea. The models were calibrated from known sets of data, using sea level data from five stations in the Baltic and one station on the Swedish west coast. These models have been in operational use at the SMHI since 1979. The west coast forecasts were not very useful in practice, partly because of the poor spatial resolution, partly because the response of sea level to variations in wind and air pressure is more direct in the Skagerrak-Kattegat than it is in the Baltic. Also, the tidal variations can be disregarded in the Baltic, but are important on the west coast. It was therefore decided to develop separate models for the Swedish west coast; these have been in operational use since July 1981.