dT: Calculates the t-derivatives for a time series

In metno/esd: Climate analysis and empirical-statistical downscaling (ESD) package for monthly and daily data

Calculates the t-derivatives for a time series

Description

dX, dY, and dT are functions to estimate derivatives for gridded field objects based on a fit to truncated Fourier series. The three functions give the x-, y- and time derivatives respectively. See Benestad, R.E. (2005) 'A review of the solar cycle length estimates' GRL 32 L15714, doi:10.1029/2005GL023621, August 13

Usage

dT(y, m = NULL, plot = FALSE, verbose = FALSE)

Arguments

y	A zoo, station or field object
m	number of harmonics for fitting the Fourier series
plot	if TRUE show plot
verbose	show diagnostics of the progress

Value

a list with several components:

Z	original data
a	Fourier coefficients for cosine
b	Fourier coeffieicnes for sine
z0	defunct?
dZ	The component contains the first derivative.
dZ2	The component contains the second derivative (quicker to do both in one go).
lon	longitude
lat	latitude
dx	spatial resolution
span	spatial extent

Examples

Rz <- Sunspots()
## Estimate the time derivative using only the gravest Fourier frequencies
d.Rz.dt <- dT(Rz,m=30)
## The original series
plot(d.Rz.dt$y)
## The fitted series
lines(d.Rz.dt$y.fit,col='red',lty=2)
## first derivative
plot(d.Rz.dt$dy)
## Second derivative
plot(d.Rz.dt$dy2)
co2 <- CO2()
dco2dt <- dT(co2)
plot(dco2dt$y)
lines(dco2dt$y.fit,col='red',lty=2)

metno/esd documentation built on April 29, 2024, 3:34 p.m.