W. Brutsaert et Dy. Chen, DIURNAL-VARIATION OF SURFACE FLUXES DURING THOROUGH DRYING (OR SEVEREDROUGHT) OF NATURAL PRAIRIE, Water resources research, 32(7), 1996, pp. 2013-2019
Experimental data recorded over a natural tallgrass prairie during the
later stages of drying in the First International Satellite Land Surf
ace Climatology Project (ISLSCP) Field Experiment-1987 showed (1) that
the total daily values of evaporation exhibited a kind of second stag
e of drying behavior with a t(-1/2) dependency at the daily timescale
and (2) that this day-to-day evolution was modulated by the available
energy at the surface, that is, the hourly radiation input. This allow
ed a simple description of the phenomenon by combining a desorptive di
ffusion-type parameterization for the total daily evaporation or for i
ts dimensionless counterpart (such as Priestley and Taylor's ct, the e
vaporative fraction, and a few others), with an assumption of self-pre
servation in the surface energy budget during the daytime hours. The r
esulting formulation, which involves two timescales, a daily and an ho
urly, was able to reproduce daytime hourly flux values over a 2-week p
eriod of intensive drying. The method can also be useful in the disagg
regation of daily, or even weekly, evaporation into hourly values.