irrad_extraterrestrial {photobiology}

Extraterrestrial irradiance

Description

Estimate of down-welling solar (short wave) irradiance at the top of the atmosphere above a location on Earth, computed based on angles, Sun-Earth distance and the solar constant. Astronomical computations are done with function sun_angles().

Usage

irrad_extraterrestrial(
  time = lubridate::now(tzone = "UTC"),
  tz = lubridate::tz(time),
  geocode = tibble::tibble(lon = 0, lat = 51.5, address = "Greenwich"),
  solar.constant = "NASA"
)

Arguments

time

A "vector" of POSIXct Time, with any valid time zone (TZ) is allowed, default is current time.

tz

character string indicating time zone to be used in output.

geocode

data frame with variables lon and lat as numeric values (degrees), nrow > 1, allowed.

solar.constant

numeric or character If character, "WMO" or "NASA", if numeric, an irradiance value in the same units as the value to be returned.

Value

Numeric vector of extraterrestrial irradiance (in W / m2 if solar constant is a character value).

See Also

Function sun_angles.

Examples

library(lubridate)

irrad_extraterrestrial(ymd_hm("2021-06-21 12:00", tz = "UTC"))

irrad_extraterrestrial(ymd_hm("2021-12-21 20:00", tz = "UTC"))

irrad_extraterrestrial(ymd_hm("2021-06-21 00:00", tz = "UTC") + hours(1:23))