albedo

hydrometlib.meteorology.albedo(swin, swout, solar_zenith_angle)

Calculate albedo [unitless fraction]

The ratio of reflected solar radiation to the total incoming solar radiation.

\[\alpha = \operatorname{clip}\!\left( \frac{SW_{out}}{SW_{in}},\; 0,\; 1 \right) \qquad \text{for } SW_{in} > 0 \text{ and } \cos\theta_s > 0\]

where \(\theta_s\) is the solar zenith angle; \(\alpha\) is null outside these conditions (for example at night).

References

• FAO-56 Chapter 3 https://www.fao.org/4/x0490e/x0490e07.htm

• https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.14048

This calculation does not account for correction due to site being on a slope.

Parameters:

• swin (Expr) – Shortwave incoming radiation [W m-2]

• swout (Expr) – Shortwave outgoing radiation [W m-2]

• solar_zenith_angle (Expr) – Solar zenith angle [radians]

Return type:

Expr

Returns:

Expression or Series for albedo. Value is null at night or where invalid, otherwise between 0 and 1.