A comparison between the ERA40 and the SMHI gridded meteorological databases as applied to Baltic Sea modelling

Abstract

Two gridded meteorological data sets for the Baltic Sea region, both having 1° × 1° horizontal resolution, were compared and analysed for use in Baltic Sea modelling. The SMHI 1° × 1° data set covers surface parameters with a three-hour time resolution over the 1970-2004 period. The ERA40 data cover analysed and modelled parameters for several atmospheric layers with a six-hour time resolution over the 1957-2002 period. Meteorological variables considered in this analysis were air temperature, wind speed, total cloud cover, relative humidity and precipitation. In considering Baltic Sea modelling, we examined maximum ice extent, water temperature, salinity and net precipitation calculations. The two data sets are largely similar and can both be use d in Baltic Sea modelling. However, their horizontal resolution is too coarse for resolving marine conditions over the Baltic Sea. This implies, for example, that the ERA40 original surface winds are too low for some Baltic Sea regions. The ERA40 precipitation values are also too low compared with those of the SMHI and other available data. © IWA Publishing 2005.