path2twilight: Compute exact astronomical twilights from a 'path' (positions...

In Rafnuss/GeoPressureR: Global Positioning by Atmospheric Pressure

Compute exact astronomical twilights from a path (positions and dates)

Description

This function compute the theoretical twilight (i.e., datetime of sunrise and sunset) at given locations and for specific date.

We use the suntools package for this.

By default (solar_dep=0), the computation return sunrise and sunset. But, it is also possible to compute different twilights by setting depression angle value greater than 0 (6° for civil, 12° for nautical and 18° for astronomical).

Usage

path2twilight(path, date = NULL, solar_dep = 0, return_long = TRUE)

Arguments

path	a GeoPressureR path or pressurepath data.frame
date	a vector of POSIXt datetime for which sunrise and sunset are computed. Be default, uses the range of path$date provided.
solar_dep	a numerical value representing the solar depression angle used to compute sunrise and sunset.
return_long	logical defining the format of the data.frame returned. If TRUE, returns the long format identical to twilight_create(). If FALSE, return the sunrise and sunset as different column, making the data.frame the same size as date.

Value

if return_long == TRUE, a twilight data.frame (same as twilight_create()) with columns:

• date same as input date

• twilight date-time of twilight

• rise logical indicating sunrise (TRUE) or sunset (FALSE).

• stap_id same as path$stap_id

• lat same as path$lat

• lon same as path$lon

if return_long == FALSE, a data.frame with the same size of date with columns:

• date same as input date

• sunrise date-time of sunrise

• sunset date-time of sunset

• stap_id same as path$stap_id

• lat same as path$lat

• lon same as path$lon

See Also

GeoPressureManual , suntools

Examples

path <- data.frame(
  stap_id = c(1, 2, 3, 4, 5),
  j = c(1L, 1L, 1L, 1L, 1L),
  ind = c(1652L, 1603L, 1505L, 1609L, 1463L),
  lat = c(48.9, 47.5, 45.5, 41.5, 37.5),
  lon = c(17.05, 16.5, 14.5, 16.5, 13.5),
  start = as.POSIXct(
    c(1501113450, 1501888650, 1501987950, 1502075550, 1502151150),
    tzone = "UTC"
  ),
  end = as.POSIXct(c(1501876050, 1501961250, 1502046750, 1502133150, 1502323050), tzone = "UTC"),
  include = c(TRUE, TRUE, TRUE, TRUE, TRUE),
  known = c(TRUE, FALSE, FALSE, FALSE, FALSE),
  interp = c(FALSE, FALSE, FALSE, FALSE, FALSE)
)

twl <- path2twilight(path)

Rafnuss/GeoPressureR documentation built on April 17, 2025, 12:58 p.m.