Ice Winter Severity in the Western Baltic Sea in the Period 1301-1500 
47 
Ice Winter Severity in the Western Baltic Sea in the Period 1301-1500 
Gerhard Koslowski 1 , Natalija Schmelzer 2 
1 Kiefernweg 10, 66606 St. Wendel, Germany 
Bundesamt für Seeschifffahrt und Hydrographie, Germany, 
E-Mail: nataliia.schmelzer@bsh.de 
Abstract 
Variations in ice winter severity in the Western Baltic in the period 1301-1500 were analysed 
analogous to an investigation of data series covering the period 1501-1700. The poor reliability 
of reconstructed ice winter severity, especially in the period from 1301 to 1400, does not allow 
us a treatment of data in the usual way. A linear relationship between the number of anomalous 
ice winters per decade and the ice winter severity index, found by Koslowski, was used to 
calculate the value of the mean ice winter index for the above period. 
Introduction 
Variations in the ice winter severity in the Western Baltic (Figure 1) were analysed and 
described by Koslowski (1989) for the period 1897-1987, and by Koslowski and Glaser (1995, 
1999) for the periods 1701-1896 and 1501-1700, supplemented by the years from 1988 to 
1995. 
Fig. 1. Map of the Western Baltic showing area under discussion