Mean long-term surface energy balance components in Finland during the summertime

The long-term, 1961–1990, mean summertime surface energy balance components in Finland were estimated by making use of earlier published studies for the estimation of the global radiation, surface albedo and latent heat flux. The net long-wave radiation was estimated with the help of synoptic cloud observations, and the sensible heat flux was calculated as the remainder in the energy balance equation. The results are presented both on a 10 km x 10 km grid and as climate-zone averages. The lowest values of global radiation, about 170 W m–2, were found in north-eastern Lapland. There was also a local minimum of about 190 W m–2 over the Suomenselkä divide and southern Ostrobothnia. The maximum values of about 220 W m–2 were found along the coast of the Baltic Sea. The cooling of the surface due to net long-wave radiation was smallest in northern Lapland, about –35 W m–2, elsewhere the spatial variation was very small, and the net long-wave radiation was from –40 to –45 W m–2. The highest values of evaporation occured in southern Finland, where the latent heat flux was about –80 W m–2, and the minimum in Lapland with a value of about –35 W m–2. The highest sensible heat fluxes were located along the coast and in Lapland, and the smallest in the inland areas of southern Finland. The difference in the sensible heat flux between the climate zones was small.