Wetland Evapotranspiration: Eddy Covariance Measurement in the Biebrza Valley, Poland

This paper presents eddy covariance measurements of evapotranspiration and sensible heat flux in wetland area. The rate of evapotranspiration is characterized by a distinct seasonal pattern and assumes the highest values during summer. From April to September, the latent heat flux is characterized by a distinct diurnal pattern with the highest average values (at the noon hours) at a level of ca 200 W·m−2. Moreover, in the period from June to August the values of latent heat flux far outweigh those of sensible heat flux (the Bowen ratio in the noon hours ranging between 0.4 and 0.6) and account for 50–60 % of radiation balance. The average daily totals of evapotranspiration vary from about 0.5 mm·d−1 during the winter months to about 3–3.5 mm·d−1 in summer.