Eccentricity factor — sol_eccentricity • fieldClim

The track of Earth around the Sun is not a circle, but more like an ellipse.

Usage

sol_eccentricity(...)

# Default S3 method
sol_eccentricity(datetime, ...)

# S3 method for class 'weather_station'
sol_eccentricity(weather_station, ...)

Arguments

...: Named station fields, site parameters or model assumptions.
datetime: POSIXlt or POSIXct date-time vector.
weather_station: A weather_station object.

Value

Unitless.

Details

The eccentricity factor ($E$) accounts for the elliptical shape of Earth's orbit around the Sun. It is calculated as: $$E = 1.00011 + 0.034221 \cdot \cos(D) + 0.00128 \cdot \sin(D) + 0.000719 \cdot \cos(2D) + 0.000719 \cdot \sin(2D)$$ where: $D$ is the day angle in radians.

References

Bendix 2004, p. 243.

Examples

# Calculate eccentricity factor
sol_eccentricity(as.POSIXlt("2022-06-21"))
#> [1] 0.9671952