et0_hg: Estimate ET0 by Hargreaves equation.

In Sibada/sibadaR: Sibada's accumulated R scripts for next probably use to avoid reinventing the wheel.

Description

Estimate reference evapotranspiration (ET0) from a hypothetical short grass reference surface using the the Hargreaves equation.

Usage

et0_hg(tmax, tmin, tmean = NULL, Ra = NULL, lat = NULL, dates = NULL)

Arguments

tmax	Daily maximum air temperature at 2m height [deg Celsius].
tmin	Daily minimum air temperature at 2m height [deg Celsius].
tmean	Daily mean air temperature at 2m height [deg Celsius]. If not provided it would estimated by averaging the tmax and tmin.
Ra	Clear sky incoming shortwave radiation, i. e. extraterrestrial radiation multiply by clear sky transmissivity (i. e. a + b, a and b are coefficients of Angstrom formula. Normally 0.75) [MJ m-2 day-1]. If not provided, must provide lat and dates.
lat	Latitude [degree].
dates	A R Date type of a vector of Date type. If not provided, it will Regard the ssd series is begin on the first day of a year.

Value

Reference evapotranspiration ET0 from a hypothetical grass reference surface [mm day-1].

Sibada/sibadaR documentation built on Jan. 31, 2020, 6:40 p.m.