search

MESH-Model / MESH-Dev

This repository contains the official MESH development code, which is the basis for the 'tags' listed under the MESH-Releases repository. The same tags are listed under this repository. Legacy branches and utilities have also been ported from the former SVN (Subversion) repository. Future developments must create 'forks' from this repository.
Other
2 stars 3 forks source link

Potential evapotranspiration issue in MESH `r1860` #47

Open kasra-keshavarz opened 4 months ago

kasra-keshavarz commented 4 months ago

Problem statement

Original posted by @MIsmlAhmed in Slack:

Hi all, I am currently revising the implementation of the prairie module in the most recent MESH version (1860). I tried using Penman-Monteith (calc_ET0 function) and the built-in CLASS POT (vs%grid%potevp) for potential evaporation calculations. However, CLASS POT seems to be 2 folds the values of the Penman-Monteith method. Is the CLASS POT really reliable to be used? Should I stick to Penman Monteith? Attached are the daily and annual POT from the two methods. I know that the values are a bit high, but that's a different story with parameterization. image image

MESH Specs

mee067 commented 4 months ago

Is that only specific to 1860? I do not think these calculations changed recently.

MIsmlAhmed commented 4 months ago

I just got those from 1860. Not sure if this is an 1860 issue or something general regardless of the used version.

mee067 commented 4 months ago

OK, I thought you used the ET thing long ago and you were the one coding Penman Monteith. Didn't do any comparisons back then?

MIsmlAhmed commented 4 months ago

I did, but CLASS POT was way off. Now, it’s a bit closer (comparable) and that’s why I wanted to ask in case something was fixed.

mee067 commented 4 months ago

As far as I know, this module was not touched. I actually do not know why would CLASS calculate PET. It solves the surface water and energy balance and this gives latent heat flux that corresponds to actual ET. PET is not needed. It's not a conceptual model.

dprincz commented 1 month ago

I think it's a known issue CLASS PET is incorrect. We've had these discussions over the years with the CLASS development group. I don't recommend using those values.

If you need PET, use the values calculated by the separate PET module.

MIsmlAhmed commented 1 month ago

@dprincz These are the values from the Penman-Monteith PET model. They are unrealistic and close to what CLASS produces.