Sea surface temperature development of the Baltic Sea in the period 1990-2004

Sea Surface Temperature (SST) maps derived from NOAA weather satellites for the period 1990-2004 were used to investigate seasonal and inter-annual variations in the Baltic Sea. A comparison between monthly mean SST and in situ measurements at the MARNET station "Arkona Sea" showed good agreement with differences in July and August. Monthly means reflect strong seasonal and inter-annual variations. The yearly means show a slight positive trend with an increase of 0.8 K in 15 years. In particular, summer and autumn months contribute to this positive trend, with stronger trends in the northern than in the southern Baltic. The winters are characterised by a slightly negative trend. The winter minimum SST in the Arkona Sea correlates best with the WIBIX climate index derived for the Baltic region.