Satellite Geolocation for Animal Tracking

Description Usage Arguments Details Value

Simulate zenith angles, times and locations of twilight along a specified track.

zenithSimulate(tm, lon, lat, tm.out)

twilightSimulate(dfz, zenith = 96)

twilightPerturb(dft, err)

`tm`	vector of times that specify the template track.
`lon`	vector of longitude that specify the template track.
`lat`	vector of latitude that specify the template track.
`tm.out`	vector of times to which the template is resampled.
`dfz`	a dataframe generated with `zenithSimulate`.
`zenith`	the solar zenith angle that defines twilight.
`dft`	a dataframe generated with `twilightSimulate`.
`err`	a vector of adjustments (in minutes) to the twilight times.

Given times, longitudes and latitudes that specify a template track, zenithSimulate interpolates the template onto the new times specified by tm.out and computes the solar zenith angle at each point along the new track. Given a dataframe generated by zenithSimulate, twilightSimulate computes times and locations of sunrise and sunset based on the simulated zenith angles. The twilightPerturb adds a given vector of errors (in minutes) to the twilights in a dataframe generated by twilightSimulate, in such a way that a positive error causes sunrise to occur later and sunset earlier.

zenithSimulate returns a data frame with components

`Date`	times along the simulated track
`Lon`	longitudes along the simulated track
`Lat`	latitudes along the simulated track
`Zenith`	zenith angles along the simulated track