Long-term results of evaporation rate in xerothermic Oak altitudinal vegetation stage in Southern Slovakia

Abstract

The paper presents the results of the model computation of actual and potential evapotranspiration as well as evaporation measurements from the GGI-3000 Pan (evaporimeter) at 3 selected stations of Slovakia for the periods 1971–2000 (2 stations) and 1986–2000 (1 station). The localities are situated in the most southern parts of Slovakia in 1^st Oak stage and on southern slopes of the Carpathian promontories. A model computation of the monthly totals of actual and potential evapotranspiration was performed by a common solution of energy and water balance equations of the top one-meter layer of the soil. The model outputs are compared to the measurement data. The dependence of the ratio of actual evapotranspiration/ evaporation measured by the GGI-3000 Pan (E/E _p) on relative evapotranspiration (E/E _o), when E, E _o are calculated, is linear with a high correlation coefficient during the season from April to October. The paper also gives the comparison results of the mean monthly and annual air temperatures, temperatures of active and saturated surface with the mean monthly temperature of free water surface in the GGI-3000 Pan at these 3 stations (Bratislava-Koliba, Somotor and Žihárec). It was found that the mean free water surface temperature for the period from April to October is close to the mean temperature of saturated surface during that period. The mean temperatures of free water surface in the GGI-3000 Pan from April to October tend to increase for the period 1971–2000.