Adding pure FAO Penman-Monteith equation to compute potential evapotranspiration

[saschahofmann]

Addressing a Problem?

The current implementation of potential_evapotranspiration makes certain assumptions about the available data e.g. saturation vapour pressure is estimated from min and max temperature or that wind speed is measured at 10m instead of two.

I would like to implement a "pure" version of equation 6 in Allen et al. 1998

I would reuse this function in the potential_evapotranspiration index to keep backwards compatibility but also make it available as an individual import. See this discussion for more information

Potential Solution

Something like this should do it

def fao_penman_monteith(net_rad, t, ws, svp, avp, delta, gamma, G):
    dividor = delta + (gamma * (1 + 0.34 * ws))
    summand1 = 0.408 *delta* (net_rad - G)
    summand2 = gamma* 900 / (t + 273.15) * ws * (svp - avp)
    return (summand1+summand2)/dividor

Additional context

No response

Contribution

• I would be willing/able to open a Pull Request to contribute this feature.

Code of Conduct

• I agree to follow this project's Code of Conduct