potential_radiation(datetime, lat, long)
potential_radiation(doy, hour, lat, long; timezone,year)

Compute potential radiation for given geolocation and time.

Because potential radiation does not change across years (for a given location and daytime and day of year), time can be specified alternatively by doy and hour.

Arguments

• datetime: UTC timestamp.
• lat: Latitude (decimal degrees)
• long: Longitude (decimal degrees)
• doy: day of year (integer starting from 1)
• hour: hour within the day (0.0 .. 24.0 float)

optional

• timezone: Timezone for doy and hour, defaults to "GMT+x" nearest to given longitude.
• year: specific year for doy and hour
• ...: other keyword arguments passed to extraterrestrial_radiation such as constants and FT

Value

vector of potential radiation (W m-2)

Examples

# assume hours in the GMT+x that is closest to given longitude
potrad = potential_radiation(160, 10.5, 51.0, 11.5)

extraterrestrial_radiation(doy::Number; ...)
extraterrestrial_radiation(datetime::TimeType; ...)

Compute the extraterrestrial solar radiation with the eccentricity correction. Computation follows Lanini, 2010 (Master thesis, Bern University).

Arguments

• doy: integer with day of year (DoY) starting at 1

optional

• constants=BigleafConstants(): Dictionary with entries
  • solar_constant
• year=2030: year to create timestamps. Due to precession results slightly change across decades.
• FT=typeof(constants.solar_constant): Specif Float type of the return value

Value

extraterrestrial radiation (W_m-2) of type FT.

Examples

ex_rad = extraterrestrial_radiation(1)
≈(ex_rad, 1414, atol = 1)

calc_sun_position_hor(datetime, lat, long)

Compute the Sun position at given time and observer coordinates in horizontal coordinates.

Arguments:

• datetime: time: Either a ZonedDateTime, or DateTime assumed in UTC
• lat, long: latitude and longitude in degree

Value

NamedTuple: sun position with entries of the same type as lat and long

• altitude: angle above the horizon [rad].
• azimuth: angle ange the horizon plane eastwards of north [rad]
• hourangle: [rad] as output by AstroLib.eq2hor Seems to represent time [day/2pi] after solar noon. Value at local timezone noon provides (local time - solar time).

calc_sun_position_MOD(JD::Number)

Compute the Sun position at the Julian Day JD.

Results are represented in the Mean Equinox of Date (MOD), i.e. accounting for precession but not for nutation and smaller perturbation of the polar axes, in spherical ecliptic and equatorial coordinates. The algorithm was adapted from [Vallado 2013, p. 277-279].

Arguments:

• JD: time given as Julian Day .

Value

NamedTuple: sun position where

• Ecliptic coordinates (1:3)
  • λ: Ecliptic longitude of the Sun [rad].
  • β: Ecliptic latitude of the Sun [rad] is assumed 0.
  • r: Distance of the Sun from Earth [m].
• Equatorial coordinate (4:5)
  • α: ascention [rad]
  • δ: declination [rad]
• ϵ: Obliquity of the ecliptic [rad].

References

• Vallado, D. A (2013). Fundamentals of Astrodynamics and Applications. Microcosm Press, Hawthorne, CA.