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Calculate global solar radiation time series at TOA

Source: R/utils.R
calc_sw_in_toa.Rd

`calc_sw_in_toa()` obtains incident global solar radiation time series at TOA (top of atmosphere) at a specific location by calculating solar elevation angle estimated from the equations of Campbell and Norman (1998).

Usage

calc_sw_in_toa(
  vctr_time,
  lat,
  lon,
  std_meridian,
  solar_const = 1365,
  sbeta_min = 0.001
)

Arguments

vctr_time

A timestamp vector of class POSIXct or POSIXt. The timestamps must be equally spaced and arranged chronologically.

lat

A numeric value (degrees) between -90 and 90, indicating the latitude of the specific location.

lon

A numeric value (degrees) between -180 and 180, indicating the longitude of the specific location.

std_meridian

A numeric value (degrees) between -180 and 180, indicating the standard meridian of the specific location.

solar_const

A positive value (W m-2) indicating the solar constant. Default is 1365 (W m-2).

sbeta_min

A threshold value of the solar elevation angle (degrees). If the calculated solar elevation angle is less than this threshold, the corresponding global solar radiation becomes zero.

Value

A vector of the global solar radiation at TOA (W m-2). The length of the vector matches that of the input timestamp vector.

Author

Yoshiaki Hata

Examples

## Make a timestamp vector
timezone <- "Etc/GMT-8"
time <- seq(as.POSIXct("2026/01/01", tz = timezone),
 as.POSIXct("2026/01/02", tz = timezone), by = "30 min")

## Obtain global solar radiation at Lambir Hills National Park in Malaysia
result <-
 calc_sw_in_toa(vctr_time = time, lat = 4.201007, lon = 114.039079,
                std_meridian = 120)