PanCoef {FAO56}

Pan Coefficient (K_p)

Description

PanCoef returns the value of Pan Coefficient (K_p).

Usage

PanCoef(u_2, RH_mean, FET, type, fetch)

Arguments

u_2

A numeric scalar that denotes the wind speed at the height 2m above the ground surface [m/s].

RH_mean

A numeric scalar that denotes the mean relative humidity. (30\% <= RH_mean <= 84\%)

FET

A numeric scalar that denotes the fetch, or distance of the identified surface type [m] (1m <= FET <= 1000m) (grass or short green agricultural crop for case A, dry crop or bare soil for case B upwind of the evaporation pan)

type

A character string that denotes the type of pan and can take the options "Class A" for Class A pan and "Colorado" for Colorado sunken pan.

fetch

A character string that denotes the fetch state and can take the options "dry" and "green".

Details

This is a function to calculate the pan coefficient used in the pan evaporation method to calculate the reference evapotranspiration.

Value

The function returns the value of the pan coefficient.

Reference

Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56. Fao, Rome, 300(9), D05109.

See Also

ETo_Pan, MeanRH.

Examples

PanCoef(u_2 = 2, RH_mean = 50, FET = 3, type = "Class A", fetch = "dry")