read.sealevel {oce} | R Documentation

## Read a sea-level data file

### Description

Read a data file holding sea level data. BUG: the time vector assumes GMT, regardless of the GMT.offset value.

### Usage

    read.sealevel(file, tz=getOption("oceTz"),
                  processingLog, debug=getOption("oceDebug"))

### Arguments

`file` | a connection or a character string giving the name of the file to load. See Details for the types of files that are recognized.
`tz` | time zone. The default value, `oceTz`, is set to `UTC` at setup. (If a time zone is present in the file header, this will supercede the value given here.)
`processingLog` | if provided, the action item to be stored in the log. (Typically only provided for internal calls; the default that it provides is better for normal calls by a user.)
`debug` | set to `TRUE` to get debugging information during processing.

### Details

This function starts by scanning the first line of the file, from which it determines whether the file is in one of two known formats: type 1, the format used at the Hawaii archive centre, and type 2, the comma-separated-value format used by the Marine Environmental Data Service. (The file type is inferred by checking for the existence of the string `Station_Name` on the first line of the file, indicating type 2.) If the file is in neither of these formats, the user might wish to scan it directly, and then to use `as.sealevel` to create a `sealevel` object.

### Value

An object of `class` `"sealevel"`, which is a `list` containing

``data``

: a list containing

`time`

  time

`eta`

  sea level [m]

``metadata``

: a list containing

`header`

  the header line or lines. (This may prove helpful if detail extraction fails.)

`year`

  year in which the observations were made.

`station.number`

  identifier for the station.

`station.version`

  see online docs at site mentioned in References.

`station.name`

  name of station

`region`

  a region code.

`latitude`

  latitude, decimal degrees, positive north of equator.

`longitude`

  longitude, decimal degrees, positive east of Greenwich.

`GMT.offset`

  offset from GMT time. This is read directly from files of type 1. For files of type 2, the offset is inferred from the timezone, but this is a somewhat risky business, since timezone names are not standard.

`decimation.method`

  see online docs at sites mentioned in References.

`reference.offset`

  a reference offset; see online docs at sites mentioned in References.

`reference.code`

  a reference code; see online docs at site mentioned in References.

`units`

  unit of observations in the original file (normally "MM")

`n`

  number of observations.

`sampling.interval`

  hours between samples in the timeseries.

``processingLog`` | : a log of processing, in the standard `oce` format.

### Author(s)

Dan Kelley

### References

The Hawaii archive site at `http://ilikai.soest.hawaii.edu/uhslc/datai.html` provides a graphical interface for downloading sealevel data in Type 1, with format as described at `http://ilikai.soest.hawaii.edu/rqds/hourly.fmt` (this link worked for years but failed at least temporarily on December 4, 2016). The MEDS repository (http://www.isdm-gdsi.gc.ca/isdm-gdsi/index-eng.html) provides Type 2 data.

### See Also

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

### Examples

    ## Not run:
    library(oce)
    # this yields the sealevel dataset
    sl <- read.oce("h275a96.dat")
    summary(sl)
    plot(sl)
    m <- tidem(sl)
    plot(m)

    ## End(Not run)

[Package oce version 0.9-18 Index]