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.

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()).

References

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

See also

The documentation for the sealevel class explains the structure of sealevel objects, and also outlines the other functions dealing with them.

Other things related to sealevel data: [[,sealevel-method, [[<-,sealevel-method, plot,sealevel-method, read.sealevel(), sealevel-class, sealevelTuktoyaktuk, sealevel, subset,sealevel-method, summary,sealevel-method

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)
#> Sealevel Summary #> ---------------- #> #> * sampling delta-t: 1 #> * Location: Lat and lon unknown #> * number of observations: 8761 #> * " non-missing: 8761 #> * Time ranges from 0000-01-01 to 0000-12-31 with 8761 samples and mean increment 1 hour #> * Data Overview #> #> Min. Mean Max. Dim. NAs OriginalName #> elevation [m] -2 0.00089588 2 8761 0 - #> #> * Processing Log #> #> - 2020-07-21 16:49:05 UTC: `create 'sealevel' object` #> - 2020-07-21 16:49:05 UTC: `as.sealevel(elevation = elevation)`
# As above, but start at the Y2K time. time <- as.POSIXct("2000-01-01") + h * 3600 sl <- as.sealevel(elevation, time) summary(sl)
#> Sealevel Summary #> ---------------- #> #> * sampling delta-t: 1 #> * Location: Lat and lon unknown #> * number of observations: 8761 #> * " non-missing: 8761 #> * Time ranges from 2000-01-01 to 2000-12-31 with 8761 samples and mean increment 1 hour #> * Data Overview #> #> Min. Mean Max. Dim. NAs OriginalName #> elevation [m] -2 0.00089588 2 8761 0 - #> #> * Processing Log #> #> - 2020-07-21 16:49:05 UTC: `create 'sealevel' object` #> - 2020-07-21 16:49:05 UTC: `as.sealevel(elevation = elevation, time = time)`