Prof. Salvucci will be talking about his work on Estimation of Evaporation from Equilibrium Diurnal Boundary Layer Humidity. Following are the key points and a relevant figure for the talk:
1) Boundary layer humidity is decreased by entrainment of dry air above the lifting condensation level.
2) To first order, this entrainment depends on the growth of the boundary layer, which is limited by surface sensible heat flux.
3) An equilibrium humidity exists for which the moistening by surface evaporation is balanced by this entrainment.
4) Data from approximately one hundred Fluxnet sites demonstrate that the atmosphere stays close enough to this equilibrium that the resulting relation can be used to estimate evaporation solely from weather data, without the need for detailed surface conditions such as soil moisture and vegetation status.