1
$\begingroup$

I am exploring FLUXNET sites for actual evapotranspiration (ETP) data (I convert the energy balance closure-corrected latent heat to ETP).

I am interested in the half-hourly data. During the night we see negative values. I would like to know the reason or physical process behind this.

Can physically-based hydrological models handle this situation? (: estimating negative half-hourly ETPs)

There are some discussion in web about how to handle the negative values of potential ETP, but not easy to find a solid discussion about the actual ETP in this case.

$\endgroup$

1 Answer 1

5
$\begingroup$

Negative values for the ET, both potential and actual, usually refer to condensation. See also "ERA5 mean evaporation rates data - Why is that negative?"

Regarding the ability of the physically-based hydrological models to handle condensation, I'd say that it's difficult to give you a general answer: it will depend on the specific math behind the model, but my general guess would be that they do. Even a simple Bucket Model, would integrate condensation in the water balance equation. While a more sophisticate Earth System Model would probably process it in the soil moisture and/or canopy component, in order to better represent these dynamics in the water-energy balance of the specific system. See for instance Longo et al 2019

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.