ar1etp: AR(1) + ETP simulation Routine

Description

Simulate a combined AR(1) + ETP signal, plot spectrum and confidence levels

Usage

ar1etp(etpdat=NULL,nsim=100,rho=0.9,wtAR=1,sig=90,tbw=2,padfac=5,ftest=F,fmax=0.1,
       speed=0.5,pl=2,graphfile=0)

Arguments

etpdat

Eccentricity, tilt, precession astronmical series. First column = time, second column = ETP. If not entered will use default series from Laskar et al. (2004), spanning 0-1000 kyr.

nsim

Number of simulations.

rho

AR(1) coefficient for noise modeling.

wtAR

Multiplicative factor for AR1 noise (1= eqivalent to ETP variance).

sig

Demarcate what confidence level (percent) on plots?

tbw

MTM time-bandwidth product.

padfac

Pad with zeros to (padfac*npts) points, where npts is the number of data points.

ftest

Include MTM harmonic f-test results? (T or F)

fmax

Maximum frequency for plotting.

speed

Set the amount of time to pause before plotting new graph, in seconds.

Plot log power (1) or linear power (2)?

graphfile

Output a pdf or jpg image of each plot? 0 = no, 1 = pdf, 2 = jpeg. If yes, there will be no output to screen. Individual graphic files will be produced for each simluation, for assembling into a movie.

Details

Note: Setting wtAR=1 will provide equal variance contributions from the etp model and the ar1 model. More generally, set wtAR to the square root of the desired variance contribution (wtAR=0.5 will generate an AR1 model with variance that is 25% of the etp model).

Note: You may use the function etp to generate eccentricity-tilt-precession models.

References

Laskar, J., Robutel, P., Joutel, F., Gastineau, M., Correia, A.C.M., Levrard, B., 2004, A long term numerical solution for the insolation quantities of the Earth: Astron. Astrophys., Volume 428, 261-285.

Examples

Run this code

# run simulations using the default settings
ar1etp()

# compare with a second model:
# generate etp model spanning 0-2000 ka, with sampling interval of 5 ka.
ex1=etp(tmin=0,tmax=2000,dt=5)
# run simulations, with rho=-.7, and scaling noise to have 50ar1etp(etpdat=ex1,rho=0.7,wtAR=sqrt(0.5))