Earthtide {earthtide}

Earthtide class

Description

Class to generate synthetic earthtide signals.

Format

An R6Class generator object

Usage

et <- Earthtide$new(
  utc = as.POSIXct("2017-01-01", tz = "UTC") + 0:(24 * 7) * 3600,
  latitude = 52.3868,
  longitude = 9.7144,
  catalog = "ksm04",
  wave_groups = data.frame(start = 0.0, end = 6.0))

et$predict(method = "gravity", n_thread = 1)
et$analyze(method = "gravity", n_thread = 1)
et$lod_tide()
et$pole_tide()
et$tide()
et$print()

Arguments

Earthtide$new

et:

An Earthtide object.

utc:

The date-time in UTC (POSIXct vector).

latitude:

The station latitude (WGS84) (degree) (numeric) defaults to 0.0

longitude:

The station longitude (WGS84) (degree) (numeric) defaults to 0.0

elevation:

The station ellipsoidal height (WGS84) (m) (numeric) defaults to 0.0

azimuth:

Earth azimuth (numeric) defaults to 0 (degrees)

gravity:

Gravity at the station (m/s^2) (numeric) 0 to estimate gravity from elevation and latitude.

earth_radius:

Radius of earth (m) (numeric) defaults to 6378136.3

earth_eccen:

Eccentricity of earth (numeric) defaults to 6.69439795140e-3

cutoff:

Cutoff amplitude for constituents (numeric) defaults to 1e-6

wave_groups:

Two column data.frame having start and end of frequency groups (data.frame). This data.frame must have two columns with the names 'start', and 'end' signifying the start and end of the wave groupings. An optional third column 'multiplier' can be provided to scale the particular wave group. If column names do no match, the inferred column positions are start, end, multiplier.

catalog:

Use the "hw95s" catalog or "ksm04" catalog (character).

eop:

User defined Earth Orientation Parameter (EOP) data.frame with the following columns: datetime, ddt, ut1_utc, lod, x, y, dx, dy

...:

Currently not used.

Earthtide$predict, Earthtide$analyze

method:

For predict and analyze. One of "gravity", "tidal_potential", "tidal_tilt", "vertical_displacement", "horizontal_displacement", "n_s_displacement", "e_w_displacement", "vertical_strain", "areal_strain", "volume_strain", "horizontal_strain" or "ocean_tides".

astro_update:

For predict and analyze. How often to update astro parameters in number of samples. This speeds up code but may make it slightly less accurate.

return_matrix:

For predict and analyze. Return a matrix of tidal values instead of data.frame. The datetime column will not be present in this case (logical).

n_thread:

For predict and analyze. Number of threads to use for parallel processing.

Details

$new(utc, latitude, longitude, elevation, azimuth, gravity,
earth_radius, earth_eccen, cutoff, wave_groups, catalog, ...)
create a new Earthtide object and initialize catalog, station and times.

$predict(method, astro_argument, return_matrix) generate a combined synthetic Earth tide.

$analyze(method, astro_argument, return_matrix, scale) generate components of the Earth tide for analysis.

$lod_tide() generate components of the LOD (Length Of Day) tide.

$pole_tide() generate components of the pole tide.

$tide() get the tide data.frame.

$print() print the Earthtide object.

References

Hartmann, T., Wenzel, H.-G., 1995. The HW95 tidal potential catalogue. Geophys. Res. Lett. 22, 3553-3556. doi:10.1029/95GL03324

Kudryavtsev, S.M., 2004. Improved harmonic development of the Earth tide-generating potential. J. Geod. 77, 829-838. doi:10.1007/s00190-003-0361-2

Wenzel, H.G., 1996. The nanogal software: Earth tide data processing package ETERNA 3.30. Bull. Inf. Marées Terrestres, 124, pp.9425-9439.

Examples

et <- Earthtide$new(
  utc = as.POSIXct("2017-01-01", tz = "UTC") + 0:(24 * 7) * 3600,
  latitude = 52.3868,
  longitude = 9.7144,
  catalog = "ksm04",
  wave_groups = data.frame(start = 0.0, end = 6.0)
)

et$predict(method = "gravity")

plot(gravity ~ datetime, et$tide(), type = "l")