plot.sealevel {oce} | R Documentation |
Plot a summary diagram for sealevel data.
## S3 method for class 'sealevel': plot(x, focus.time=NULL, ...)
x |
A sealevel object, e.g. as read by read.sealevel . |
focus.time |
if provided, the the time interval on which to focus, each a string in a format suitable for interpretation by as.POSIXct ; see the example. |
... |
optional arguments passed to plotting functions. |
Creates a plot for a sea-level dataset, in one of two varieties.
If a focus.time
is provided, then the plot is a simple time
series extending between the two times.
If a focus.time
is not not provided, then a multi-panel display
is drawn. The top panel shows the entire timeseries; since this
typically extends over a year, the graph mainly shows low-frequency
modulations of the tide, such as spring-neap cycles. The second panel
focusses on the first month of data, providing a quick visual signal
as to the nature of the tide, e.g. mainly semidiurnal, mainly diurnal,
or mixed. In both of these panels, the sealevel is plotted as an
anomaly in excess of the mean over the whole timeseries. This mean
value is indicated in the right-hand margin. If the sealevel series
contains missing values, then only these two panels are
drawn. However, if it has no missing values, then two spectral
representations are also drawn. The first of these is a power
spectrum, with some common tidal constituents being indicates with
lines and labels. The units are m^2 per cycle-per-day. The
second, and thus the lower of the four panels, is a cumulative graph
of the square root of the power spectrum. The unit for this graph is
m, so that the step for each tidal constituent may be
interpreted as the amplitude of that constituent, and the largest
value on the graph gives the standard deviation of sealevel height.
None.
Dan Kelley
The example refers to Hurricane Juan, which caused a great deal of damage to Halifax in 2003. Since this was in the era of the digital photo, a casual web search will uncover some spectacular images of damage, from both wind and storm surge. The wikipedia entry http://en.wikipedia.org/wiki/Hurricane_Juan provides a good entry to the topic, with the Canadian Hurricane Centre's http://www.atl.ec.gc.ca/weather/hurricane/juan/summary_e.html filling in some more technical details.
summary.sealevel
summarizes the information, while
read.sealevel
scans it from a file.
library(oce) data(sealevel.hal) # Overall plot plot(sealevel.hal) # Focus on 2003-Sep-28 to 29th, the time when Hurricane Juan caused flooding plot(sealevel.hal, focus.time=c("2003-09-23","2003-10-05")) abline(v=as.POSIXct("2003-09-28 23:30:00"), col="red", lty="dotted") mtext("Hurricane\nJuan", at=as.POSIXct("2003-09-28 23:30:00"), col="red")