Calculates the sunrise and sunset hours for a specific date and location

Returns the sunrise and sunset hours for specified dates within a bounding box based on sun ephemerides calculations. Sunrise is calcualted using the midpoint of the east edge of the bounding box while sunset is calculated using the midpoint of the west edge.

The bounding box may be specified via any of the following methods:

  • Olson timezone, either as part of a POSIXt datetime, or specified via the timezone parameter

  • Geographic Bounding Box, either as a vector of floats in c(lonLo, lonHi, latLo,latHi) order, or the return value from sp::bbox(), or raster::extent()

  • Longitude and Latitude specified in decimal degrees

If more than one of the above are specified, the order of preference for determining the bounding box is:

  1. longitude, latitude passed in -- location +/- 0.1 degrees

  2. bbox passed in -- use unchanged

  3. timezone passed in -- use bbox of the timezone

  4. datetime is POSIXct -- use bbox of the timezone attribute

getDaylightHours(
  datetime = NULL,
  longitude = NULL,
  latitude = NULL,
  bbox = NULL,
  timezone = NULL,
  isJulian = FALSE
)

Arguments

datetime

Specific date for which daylight hours are requested.
longitude

Longitude of the location of interest in decimal degrees E.
latitude

Latitude of the location of interest in decimal degrees N.
bbox

Bounding box for the region of interest, Default: CONUS.
timezone

Timezone in which to interpret the datetime.
isJulian

Logical value determining whether datetime should be interpreted as a Julian date with day of year as a decimal number.

Value

List containing POSIXct sunrise and sunset times for the specified date.

Examples

# \donttest{
library(MazamaSatelliteUtils)
library(MazamaSpatialUtils)

# Get sunrise and sunset by lat/lon and datetime
getDaylightHours(
  datetime = "2019-09-06",
  longitude = -123.245,
  latitude = 42.861
)
#> $sunrise
#> [1] "2019-09-06 06:42:25 PDT"
#> 
#> $sunset
#> [1] "2019-09-06 19:39:05 PDT"
#> 

# Get sunrise and sunset by bbox and datetime
getDaylightHours(
  datetime = "2019-09-06",
  bbox = c(-124.566, -116.463, 41.991, 46.292)
) # Oregon
#> $sunrise
#> [1] "2019-09-06 06:14:30 PDT"
#> 
#> $sunset
#> [1] "2019-09-06 19:45:28 PDT"
#> 

# Get sunrise and sunset by datetime and timezone
getDaylightHours(
  datetime = "2019-09-06",
  timezone = "America/Los_Angeles")
#> $sunrise
#> [1] "2019-09-06 06:07:52 PDT"
#> 
#> $sunset
#> [1] "2019-09-06 19:43:11 PDT"
#> 

# Get sunrise and sunset for a vector of datetimes
getDaylightHours(
  datetime = c("2019-06-21", "2019-09-23", "2019-12-22"),
  longitude = -123.245,
  latitude = 42.861
)
#> $sunrise
#> [1] "2019-06-21 05:33:49 PDT" "2019-09-23 07:00:52 PDT"
#> [3] "2019-12-22 07:40:45 PST"
#> 
#> $sunset
#> [1] "2019-06-21 20:55:21 PDT" "2019-09-23 19:08:41 PDT"
#> [3] "2019-12-22 16:42:01 PST"
#> 
# }