A computation of the evaporation in Southern Sweden during 1957

The monthly evaporation during 1957 from a region in Southern Sweden has been computed by means of studies of the precipitation and the net influx of water vapour into the area. Upper air charts have been used and from the geostrophic winds and humidity values the net flux has been computed twice a day. Various sources of error have been discussed, among them the effect of the ageostrophic component of the wind which for various reasons had to be neglected. No definite conclusion as to the importance of the ageostrophic component has been reached, but it seems likely that the errors caused are not very large in this area.

The method seems useful even over the rather small area studied, but an improved network with denser observations is desirable. The evaporation was largest during July and August and smallest during the winter months. The contribution to the run-off was largest during July-October. During April and May the evaporation was even larger than the precipitation.

The yearly value of evaporation agreed well with estimates from hydrologic studies.