Spatial distribution of meso-scale precipitation in Scania, southern Sweden

The aim of this study is to analyse the spatial variability of meso-scale precipitation in Scania and to assess the influence of synoptic scale atmospheric circulation. The modes of spatial variation are revealed by EOF analysis of monthly precipitation totals between 1963 and 1990, which were obtained from a dense rain-gauge network in Scania. southern Sweden. The influence of local physiography on the spatial distribution of precipitation is assessed by GIS techniques using a digital elevation model of Scania. The relation to synoptic scale atmospheric circulation is analysed using regional circulation indices and weather types. It is shown that the daily precipitation distribution in the area is significantly influenced by synoptic scale pressure patterns. Nevertheless. the covariability of the monthly precipitation within Scania is high. About 80% of the precipitation variability is connected to the passage of low-pressure centres over or close to the region. which are likely to produce precipitation over the whole area. A wind-direction dependency found in the distribution indicates that there might be a limit between precipitation regimes within the landscape. Topography greatly influences the spatial distribution in Scania. The distribution of land and surrounding sea is also an important factor and makes the relationship between physiography and precipitation rather complex. The physiographical effects vary over a single year. The dampening effect of the sea on the atmospheric temperature influences the local stability in coastal areas and results in seasonally dependent precipitation patterns.