(Photo © Gigi Cohen)

Dr. Stephen R. Meyers
Vilas Distinguished Professor

Department of Geoscience

Ph.D., Northwestern University, 2003

Research Areas:
Paleoclimatology & Paleoceanography, Quantitative Stratigraphy, Sedimentary Geochemistry, Computational Statistics & Data Analysis

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Astrochron: A Computational Tool for Astrochronology

Astrochron is an "open-source" computational platform for conducting, and learning about: (1) paleoclimate time series analysis, (2) astronomical time scale construction, and (3) the statistical integration of astrochronologies with other geochronologic/chronostratigraphic data (e.g., radioisotopic geochronology). An ultimate goal of the project is to facilitate efficient and transparent communication of the analytical approaches used, enabling rapid verification of results, while fostering science & methodological innovation through community involvement. Astrochron is written for R, the free software for statistical computing and graphics.

Since its launch in 2014, Astrochron has grown to include a wide range of statistical tools for paleoclimate time series analysis, chronostratigraphy and geochronology, including numerous statistical approaches developed by our research group. Astrochron also provides an integrated learning environment for instruction on the software — and the mathematical/statistical concepts that underlie the analyses — through manuals, tutorials and modeling tools.

The software incorporates functions that fall into eight basic categories: (1) data preparation, (2) spectral analysis, (3) astrochronologic testing and time scale construction, (4) filtering, (5) data visualization and general R tools, (6) radioisotope geochronology, (7) modeling and educational tools, (8) other statistical methods.

See these instructions for the installation of R and Astrochron: PDF

See this graphic for a summary of the functions available in Astrochron: PDF

You can find the official CRAN Astrochron manual here: PDF

The latest public beta (version 0.9) is available for download from CRAN.

If you use Astrochron, please cite it as:
Meyers, S.R. (2014). Astrochron: An R Package for Astrochronology. https://cran.r-project.org/package=astrochron

Version 0.9 of Astrochron includes the following improvements:
  • ar1etp - updated plots (option pl), and added option to exclusively evaluate noise (wtAR<0)
  • detrend - added option to output linear trend
  • diffAccum - model differential sediment accumulation across lithofacies
  • getData - added data sets 607-18O, AEB-18O, Newark-rank, CDL-rank, DVCP2017-18O
  • getLaskar - added 65 deg. North insolation, summer solstice
  • imbrie - an implementation of the Imbrie and Imbrie (1980) ice sheet model
  • lowspec - added option to allow log frequency plotting (option pl).
  • mtm - added option to allow log frequency plotting (option pl).
  • mtmML96 - added option to allow log frequency plotting (option pl).
  • mtmPL - added option to allow log frequency plotting (option pl); corrected for round-off error on default flow estimation
  • multiTest - added output option
  • read - added verbose option; if averaging is performed, original data points are plotted for comparison.
  • sortNave - if averaging is performed, original data points are plotted for comparison.
  • synthStrat - synthesize stratigraphy from forcing function
  • testPrecession - significance testing algorithm updated
  • testTilt - astrochronologic testing via the obliquity amplitude modulation approach of Zeeden et al. (2019 submitted).
  • timeOptTemplate - timeOpt approach with sedimentation templates of Meyers (2019)
  • timeOptTemplateSim - significance testing for timeOptTemplate (Meyers, 2019)
  • tune - added new warning message when control has only one line
  • Other assorted code/documentation improvements
  • Version 0.8 of Astrochron includes the following improvements:
  • calcPeriods - calculate eccentricity and precession periods in ka, given g and k in arcsec/yr
  • confAdjust - adjust spectrum confidence levels for multiple comparisons, using the Bonferroni correction
  • eTimeOpt - evolutive implementation of timeOpt
  • eTimeOptTrack - track eTimeOpt maxima
  • makeNoise - generate noise surrogates from a theoretical power spectrum
  • mtmPL - multitaper method (MTM) spectral analysis with power law (1/f) fit
  • multiTest - adjust spectral p-values for multiple comparisons, using a range of approaches
  • pwrLaw - generate power law (1/f) noise surrogates, following the algorithm of Timmer and Konig (1995)
  • pwrLawFit - estimate power law (1/f) fit to power spectrum, following the algorithm of Vaughan (2005)
  • testBackground - a simulation tool to evaluate power spectrum false positive rates, etc.
  • timeOptMCMC - Markov-Chain Monte Carlo timeOpt approach of Meyers & Malinverno (2018)
  • tracePeak - a tool to interactively trace peak trajectories on plots
  • trackPeak - a tool to interactively select points to track peak trajectories on plots
  • timeOptSim - now implements a new p-value estimation procedure
  • Other assorted code/documentation improvements
  • Version 0.7 of Astrochron includes the following improvements:
  • slideCor - identify optimal spatial/temporal shift to maximize correlation between two stratigraphic series
  • mwin - determine 'dynamic moving window' for stratigraphic series, adjusting for changing sample density to maintain a window of constant duration
  • mwCor - calculate moving window correlation coefficient for two stratigraphic series, using a 'dynamic window'
  • mwStats - 'dynamic window' moving average, median and variance of stratigraphic series
  • timeOptPlot - generate summary figure for TimeOpt analyses
  • timeOpt - new features added
  • Other assorted code/documentation improvements
  • Version 0.6.6 of Astrochron includes the following improvements:
  • 'Native routine registration' has been updated to be compliant with CRAN standards
  • eha & plotEha include new color palettes, which are compatible with the formatting used by the journal Nature.
  • timeOpt includes a new graphical output when one sedimentation rate is investigated
  • Other minor code improvements
  • Version 0.6.5 of Astrochron is a minor upgrade, with assorted modifications to improve performance.

    Version 0.6 of Astrochron includes the following improvements:
  • surrogateCor - a new statistical approach to estimate the correlation coefficient and associated p-value for two stratigraphic data sets with different sampling grids (Baddouh et al., 2016, EPSL)
  • rmNA - remove stratigraphic levels from your data frame if they contain one or more NAs.
  • mtm - now outputs 90%, 95% and 99% AR1 confidence levels, when output=1.
  • mtmML96 - now outputs 90%, 95% and 99% robust AR1 confidence levels, when output=1.
  • Assorted code improvements
  • Version 0.5 of Astrochron includes the following improvements:
  • timeOpt - evaluation of eccentricity-related amplitude modulation and bundling in paleoclimate data using the method of Meyers (2015, Paleoceanography)
  • getData - Download data files from the astrochron server
  • Assorted code improvements
  • Version 0.4.3 of Astrochron is a minor upgrade.

    Version 0.4.2 of Astrochron includes the following improvements:
  • testPrecession - the Zeeden et al. (2015, Paleoceanography) amplitude modulation test
  • mtmML96 - a new version of the Mann and Lees (1996) robust red noise approach that solves the "edge effect" problem (see Meyers, 2012)
  • mtmAR - test your spectrum against higher order AR models (the "intermediate spectrum" test of Thomson et al. (2001))
  • integratePower - integrate evolutionary power spectra
  • taner - Taner bandpass/lowpass filter
  • surrogates - generate phase randomized surrogates as in Ebisuzaki (1997)
  • getLaskar - automatically download Laskar et al. astronomical solutions (LA04, LA10a, LA10b, LA10c, LA10d, LA11)
  • stepHeat - evaluate incremental heating Ar/Ar data
  • wtMean - evaluate total fusion Ar/Ar data
  • Code optimization throughout, to speed things up!
  • Page last updated January 9, 2019

    Unless otherwise noted, all content © S. Meyers