sirad (version 2.0-2)

ha: Hargreaves solar radiation model

Description

'ha()' calculates daily solar radiation based on daily temperature range using Hargreaves model.

Usage

ha(days, lat, A, B, Tmax, Tmin)

Arguments

days

Vector of class 'Date' of length n.

lat

Latitude in decimal degrees.

A

Hargreaves model coefficient 'A'.

B

Hargreaves model coefficient 'B'.

Tmax

Vector of length n containing daily maximum temperature [C].

Tmin

Vector of length n containing daily minumum temperature [C].

Value

• Vector of length n of daily solar radiation [MJm-2].

Details

Hargreaves proposed a method for estimating solar radiation from air temperature measurements.

References

Hargreaves, G.H., Samini, Z.A.. 1892. Estimating potential evapotranspiration. J. Irrig. Darin. Eng., ASCE 108 (3), 225-230.

See Also

'hacal' to calibrate model using reference data, 'bc' to use Bristow-Campbell model to calculate solar radiation based on temperature range.

Examples

require(zoo)
data(Metdata)
tmax <- Metdata$meteo$TEMP_MAX
tmin <- Metdata$meteo$TEMP_MIN
days <- Metdata$meteo$DAY
lat <- Metdata$LATITUDE
plot(zoo(ha(days=days, lat=lat, A=0.17, B=0, Tmax=tmax, Tmin=tmin),order.by=days))