ERA5 mean evaporation rates data - Why is that negative?
Just leaving this for future readers. I finally found in some ECMWF documentation (referring to a different variable) that: "The ECMWF Integrated Forecasting System convention is that downward fluxes are positive. Therefore, negative values indicate evaporation and positive values indicate condensation". This applies also to other variables.
Thanks to Daniel and Spencer for their help.