sw.N2 {oce} | R Documentation |
Compute N^2, the square of the buoyancy frequency for a seawater profile.
buoy.freq.2 <- sw.N2(p, sigma.theta, ...)
p |
in-situ pressure [dbar] |
sigma.theta |
Surface-referenced potential density minus 1000 [kg/m^3] |
... |
Extra arguments that will be passed to
smooth.spline if supplied. A common example is to set df ,
the degrees of freedom for the spline fit; if not set, this will be set
to the value length(p)/4 . |
The result is calculated from the derivative of a smoothing cubic
spline fitted to the density profile using smooth.spline
.
Optional arguments in ... are passed to this routine, and this gives
the user a great deal of control over the smoothing technique; see
the documentation on smooth.spline
for details. For
example, plot.profile
uses df=length(x$p)/4
as an
optional argument to N2
to do some smoothing of the
density profile.
Square of buoyancy frequency [radian/s].
Dan Kelley Dan.Kelley@Dal.Ca
library(oce) data(ctd) p <- ctd$data$pressure sigthe <- sw.sigma.theta(ctd$data$temperature, ctd$data$salinity, ctd$data$pressure) par(mfcol=c(3,1)) plot(sigthe, -p) lines(sigthe, -p) plot(sw.N2(p,sigthe), -p) lines(sw.N2(p,sigthe), -p) abline(v=0) # Demonstrate the effect of the df parameter in smooth.spline() lines(sw.N2(p,sigthe,df=length(p)/4), -p) abline(v=0)