The Geostrophic Component

Abstract

In this chapter the geostrophic component (gt) is analysed and related to the synoptic pressure field. A simple model is proposed to predict the geostrophic wind from the configuration of low and high pressure systems, and to establish the extent of association between this wind, which describes a meteorological phenomenon, and the geostrophic component (gt) obtained in the last chapter by filtering the raw data series (wt). It is shown that the model is fairly robust towards its parameterization and that it achieves a good agreement between (gt) and the predicted geostrophic wind despite its simplicity. It can therefore be assumed that (gt) captures the main characteristics of the geostrophic wind and that the initial decomposition is physically meaningful. We then go on to specify particular synoptic configurations in terms of wind speed and direction, which will be referred to as synoptic states. The objective is to find regularities in the passage of high and low pressure systems, and to establish basic weather patterns. It is demonstrated that a complete partition of (gt) into the synoptic states roughly reflects the seasonal weather patterns as outlined in section 1.2.