etp: Generate eccentricity-tilt-precession models

In astrochron: A Computational Tool for Astrochronology

Generate eccentricity-tilt-precession models

Description

Calculate eccentricity-tilt-precession time series using the theoretical astronomical solutions. By default, the Laskar et al. (2004) solutions will be downloaded. Alternatively, one can specify the astronomical solution.

Usage

etp(tmin=NULL,tmax=NULL,dt=1,eWt=1,oWt=1,pWt=1,esinw=T,solution=NULL,standardize=T,
     genplot=T,verbose=T)

Arguments

tmin	Start time (ka before present, J2000) for ETP. Default value is 0 ka, unless the data frame 'solution' is specified, in which case the first time datum is used.
tmax	End time (ka before present, J2000) for ETP. Default value is 1000 ka, unless the data frame 'solution' is specified, in which case the last time datum is used.
dt	Sample interval for ETP (ka). Minimum = 1 ka.
eWt	Relative weight applied to eccentricity solution.
oWt	Relative weight applied to obliquity solution.
pWt	Relative weight applied to precession solution.
esinw	Use e*sinw in ETP calculation? (T or F). If set to false, sinw is used.
solution	A data frame containing the astronomical solution to use. The data frame must have four columns: Time (ka, positive and increasing), Precession Angle, Obliquity, Eccentricity.
standardize	Standardize (subtract mean, divide by standard deviation) precession, obliquity and eccentricity series before applying weight and combining? (T or F)
genplot	Generate summary plots? (T or F).
verbose	Verbose output? (T or F).

Details

Note: If you plan to repeatedly execute the etp function, it is advisable to download the astronomical solution once using the function getLaskar.

Note: It is common practice to construct ETP models that have specified variance ratios (e.g., 1:1:1 or 1:0.5:0.5) for eccentricity, obliquity and precession. In order to construct such models, it is necessary to choose 'standardize=T', and to set the individual weights (eWt, oWt, pWt) to the square root of the desired variance contribution.

Value

Eccentricity + tilt + precession.

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.

Laskar, J., Fienga, A., Gastineau, M., Manche, H., 2011, La2010: A new orbital solution for the long-term motion of the Earth: Astron. Astrophys., Volume 532, A89.

Laskar, J., Gastineau, M., Delisle, J.-B., Farres, A., Fienga, A.: 2011, Strong chaos induced by close encounters with Ceres and Vesta: Astron. Astrophys., Volume 532, L4.

See Also

getLaskar

Examples

 ## Not run: 
# create an ETP model from 10000 ka to 20000 ka, with a 5 ka sampling interval
# this will automatically download the astronomical solution
ex=etp(tmin=10000,tmax=20000,dt=5)

# alternatively, download the astronomical solution first
ex2=getLaskar()
ex=etp(tmin=10000,tmax=20000,dt=5,solution=ex2)
 
## End(Not run)

astrochron documentation built on Sept. 30, 2024, 9:14 a.m.