ERA5-Land : evaporation from open water surfaces excluding oceans (evaow)

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1

For a forecast study, I am using ERA5-Land “evaporation from open water surfaces excluding oceans”. I am considering modelling this flux using a Penman / Penman–Monteith formulation for open water.

Since ERA5-Land follows the ECMWF convention where downward fluxes are positive (i.e. evaporation is negative), I would like to ask:

  • Is Penman–Monteith an appropriate physical representation of this variable?
  • Is applying a simple sign change sufficient to make Penman-based evaporation consistent with ERA5-Land outputs?

Any insights from those familiar with ERA5-Land or IFS land-surface fluxes would be very helpful.