Catchment‐scale evaporation and the atmospheric boundary layer

Evaporation is an important component of the hydrological cycle; for example, over land surfaces it amounts on average to about 60% of precipitation. This means that for hydrological purposes such as water budget calculations, the prediction or forecasting of floods and droughts, and for dynamic weather forecasting and climate modeling, it is indispensable to have reliable information on land surface evaporation. In mapping a strategy for this, decisions must be made regarding the scales at which this phenomenon is best parameterized. The atmosphere has the capacity of integrating and smoothing the effects of small‐scale irregularities over larger areas. Therefore a more thorough understanding of turbulent transport mechanisms in the atmospheric boundary layer should lead to improved parameterization methods of evaporation at the regional and watershed scale.