evapotranspiration_from_latent_heat_flux#

hydrometlib.evapotranspiration.evapotranspiration_from_latent_heat_flux(le, ta)[source]#

Evapotranspiration (ET) from latent heat flux [mm h-1]

The latent heat flux is the energy used to evaporate water, \(LE = \lambda \, ET\), so dividing it by the latent heat of vaporization gives the evapotranspiration rate:

\[ET = \frac{LE}{\lambda}\]

where \(LE\) is the latent heat flux [W m-2] and \(\lambda\) is the latent heat of vaporization [MJ kg-1] at air temperature \(T_a\). \(LE\) can be measured directly by eddy covariance, or estimated as the residual of the surface energy balance with latent_heat_flux().

Unit conversion: \(\lambda\) is multiplied by \(10^{6}\) to convert it from MJ kg-1 to J kg-1, giving \(ET\) as a mass flux of water [kg m-2 s-1]. Taking the density of water as 1000 kg m-3, 1 kg m-2 of water is a depth of 1 mm, so this is also a depth rate [mm s-1], which is multiplied by 3600 to give mm h-1.

References

Parameters:

  • le (Expr) – Latent heat flux [W m-2]

  • ta (Expr) – Air temperature [degC]

Return type:

Expr

Returns:

Expression or Series computing ET [mm h-1]