computeIsDayByLocation: computeIsDayByLocation

In solartime: Utilities Dealing with Solar Time Such as Sun Position and Time of Sunrise

Description

tell for each timestamp, whether its daytime

Usage

computeIsDayByLocation(timestamp, latDeg, 
    longDeg, timeZone = getHoursAheadOfUTC(timestamp), 
    duskOffset = 0, isCorrectSolartime = TRUE)

Arguments

timestamp	POSIXct vector
latDeg	Latitude in (decimal) degrees
longDeg	Longitude in (decimal) degrees
timeZone	Time zone (in hours) ahead of UTC (Central Europe is +1)
duskOffset	integer scalar: time in hours after dusk for which records are still regarded as day
isCorrectSolartime	set to FALSE to omit correction between local time and solar time, e.g. if coordinates cannot be provided

Details

computes hour of sunrise and sunset from given date in timezone hour (assuming dates are given in timezone instead of solartime)

Value

logical vector (length(date)): true if its daytime

Author(s)

Thomas Wutzler

Examples

dateSeq <- seq( as.POSIXct("2017-03-20", tz = "Etc/GMT-1")
                ,as.POSIXct("2017-03-21", tz = "Etc/GMT-1")
                , by = "30 min")
tmp <- computeIsDayByLocation(
  dateSeq, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
plot( tmp ~ dateSeq )
yday <- as.POSIXlt(dateSeq[1])$yday + 1L
sunrise <- computeSunriseHourDoy(
  yday, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
sunset <- computeSunsetHourDoy(
  yday, latDeg = 50.93, longDeg = 11.59, timeZone = 1)
abline( v = trunc(dateSeq[1], units = "days") + c(sunrise,sunset)*3600L )

solartime documentation built on April 22, 2021, 5:10 p.m.