CSSRad {FAO56}

Clear-Sky Solar Radiation (R_so)

Description

CSSRad returns the value of clear-sky solar radiation.

Usage

CSSRad(a_s = 0.25, b_s = 0.5, elev = NULL, R_a)

Arguments

a_s

Optional. A numeric scalar that denotes regression constant, expressing the fraction ofextraterrestrial radiation reaching the earth on overcast days (n = 0). The default is a_s = 0.25.

b_s

Optional. A numeric scalar that denotes fraction of extraterrestrial radiation reaching the earth on clear days (n = N). The default is b_s = 0.5

elev

Optional. A numeric scalar that denotes the elevation above the sea level [m].

R_a

A numeric scalar that denotes extraterrestrial radiation [MJ/(m^2\times day)]

Details

This is a function to calculate the clear-sky solar radiation. The argument elev is needed when the calibrated values of a_s and b_s are not available.

Value

The function returns the value of clear-sky solar radiation as a numeric scalar.

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

ExRad.

Examples

CSSRad(a_s = 0.27, b_s = 0.48, R_a = 25.1)
CSSRad(elev = 100, R_a = 25.1)