oce (version 0.1-82)

sealevel.tuk: Sea-level data set, from Tuktoyaktuk (1975)

Description

This sea-level dataset is provided with in Appendix 7.2 of Foreman (1977) and also with the T_TIDE package (Pawlowicz et al., 2002). It results from measurements made in 1975 at Tuktoyaktuk, Northwest Territories, Canada.

The data set is a test contains 1584 points, some of which have NA for sea-level height. The first point in the set is at time 1975-07-06 0800 GMT. However, the first 15 points of the series have NA for the sealevel value, so that the first non-missing point is at 2300 GMT, or 1600 MST as in Foreman's Appendix 7.2.

Usage

data(sealevel.tuk)

source

The data were extracted from the T_TIDE dataset (which Pawlowicz et al. (2002) seems to have based on Appendix 7.2 of Foreman (1977), to build a test case), edited a bit to get the dates in a format that Rcould scan, and put into a data file. This file was then used to create sealevel object follows.)

# Note: the data file is not supplied with the package, # and the 7h offset is to convert from Mountain Standard Time. tuk <- read.table("tuk/tuk_time_elev.dat", header=FALSE, as.is=TRUE) time <- as.POSIXlt( strptime(tuk$V1, "%d-%b-%Y %H:%M:%S", tz="GMT") + 7*3600, tz="GMT") eta <- tuk$V2 sealevel.tuk <- as.sealevel(eta=eta, time=time, station.name="Tuktoyaktuk", region="NWT", station.number=6485, longitude=133.0292, latitude=69.43889, year=1975, GMT.offset=0) #save(sealevel.tuk, file="oce/data/sealevel.tuk.rda")

References

Foreman, M. G. G., 1977. Manual for tidal heights analysis and prediction. Pacific Marine Science Report 77-10, Institute of Ocean Sciences, Patricia Bay, Sidney, BC, 58pp.

Pawlowicz, Rich, Bob Beardsley, and Steve Lentz, 2002. Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE. Computers and Geosciences, 28, 929-937.

Examples

data(sealevel.tuk)
plot(sealevel.tuk$data$time, sealevel.tuk$data$elevation, type='l',
     ylab="Height [m]",ylim=c(-2,6))
legend("topright", legend=c("Tuktoyaktuk (1975)","Detided"),
       col=c("black","red"),lwd=1)
tide <- tidem(sealevel.tuk)
detided <- sealevel.tuk$data$elevation - predict(tide)
lines(sealevel.tuk$data$time, detided, col="red")