Evaporation in relation to CO2 concentration: Analysis of mass transfer coefficient

In this study, the potential of mass transfer approach in estimating evaporation changes under different CO2 levels are evaluated using data from controlled chamber experiments in which radiation and wind velocity were kept constant and temperature and relative humidity profiles were varied in different patterns along with CO2 concentration. Currently, FAO procedure lists three approaches to compute air vapour pressure based on temperature and relative humidity profiles. In this study, the impact of using different procedures of estimating air vapour pressure is examined to assess the use of mass transfer approach for estimating evaporation. To achieve this, a part of the data is used to calibrate mass transfer coefficient which is subsequently used to project evaporation for future states. Accordingly, strategies are ranked for their potential in estimating evaporation. The effect of evaporation rate is compared at 400 ppm and 600 ppm CO2 level. It has been observed that the evaporation rate is more pronounced at higher CO2 level.

► The evaporation at 600 ppm CO2 concentration is higher than at 400 ppm. ► Mass transfer approach is a potential estimator of evaporation. ► Several strategies are evaluated to estimate the mass transfer coefficient. ► Best performing strategy is identified.