as.sealevel: Coerce Data Into a sealevel Object
In oce: Analysis of Oceanographic Data

as.sealevel

R Documentation

Coerce Data Into a sealevel Object

Description

Coerces a dataset (minimally, a sequence of times and heights) into a sealevel dataset. The arguments are based on the standard data format, as were described in a file formerly available at reference 1.

Usage

as.sealevel(
  elevation,
  time,
  header = NULL,
  stationNumber = NA,
  stationVersion = NA,
  stationName = NULL,
  region = NULL,
  year = NA,
  longitude = NA,
  latitude = NA,
  GMTOffset = NA,
  decimationMethod = NA,
  referenceOffset = NA,
  referenceCode = NA,
  deltat
)

Arguments

`elevation`	a list of sea-level heights in metres, in an hourly sequence.
`time`	optional list of times, in POSIXct format. If missing, the list will be constructed assuming hourly samples, starting at 0000-01-01 00:00:00.
`header`	a character string as read from first line of a standard data file.
`stationNumber`	three-character string giving station number.
`stationVersion`	single character for version of station.
`stationName`	the name of station (at most 18 characters).
`region`	the name of the region or country of station (at most 19 characters).
`year`	the year of observation.
`longitude`	the longitude in decimal degrees, positive east of Greenwich.
`latitude`	the latitude in decimal degrees, positive north of the equator.
`GMTOffset`	offset from GMT, in hours.
`decimationMethod`	a coded value, with 1 meaning filtered, 2 meaning a simple average of all samples, 3 meaning spot readings, and 4 meaning some other method.
`referenceOffset`	?
`referenceCode`	?
`deltat`	optional interval between samples, in hours (as for the `ts()` timeseries function). If this is not provided, and `t` can be understood as a time, then the difference between the first two times is used. If this is not provided, and `t` cannot be understood as a time, then 1 hour is assumed.

Value

A sealevel object (for details, see read.sealevel()).

Author(s)

Dan Kelley

References

⁠http://ilikai.soest.hawaii.edu/rqds/hourly.fmt⁠ (this link worked for years but failed at least temporarily on December 4, 2016).

Examples

library(oce)

# Construct a year of M2 tide, starting at the default time
# 0000-01-01T00:00:00.
h <- seq(0, 24 * 365)
elevation <- 2.0 * sin(2 * pi * h / 12.4172)
sl <- as.sealevel(elevation)
summary(sl)

# As above, but start at the Y2K time.
time <- as.POSIXct("2000-01-01") + h * 3600
sl <- as.sealevel(elevation, time)
summary(sl)

oce documentation built on Sept. 11, 2024, 7:09 p.m.