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Evaporation estimates using weather station data and boundary layer theory
Author(s) -
Gentine P.,
Chhang A.,
Rigden A.,
Salvucci G.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070819
Subject(s) - evapotranspiration , sensible heat , latent heat , environmental science , humidity , evaporation , boundary layer , atmospheric sciences , evaporative cooler , meteorology , moisture , planetary boundary layer , eddy covariance , geology , geography , turbulence , mechanics , ecology , physics , ecosystem , biology
Global estimates of evapotranspiration remain a challenge. In this study, we show that the daily course of air temperature and specific humidity available at routine weather stations can be used to estimate evapotranspiration and the evaporative fraction, the ratio of latent heat flux to available energy at the surface. Indeed, the diurnal increase in air temperature reflects the magnitude of the sensible heat flux and the increase of specific humidity after sunrise reflects the amplitude of evapotranspiration. The method is physically constrained and based on the budget of heat and moisture in the boundary layer. Unlike land surface‐based estimates, the proposed boundary layer estimate does not rely on ad hoc surface resistance parameterizations (e.g., Penman‐Monteith). The proposed methodology can be applied to data collected at weather stations to estimate evapotranspiration and evaporative fraction under cloudy conditions and in the pre–remote sensing era.