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This repository provides code to reproduce the figures of "Probing the timescale dependency of local and global variations in surface air temperature from climate simulations and reconstructions of the last millennia" (Ellerhoff and Rehfeld, 2021) published in Physical Review E (2021).

URL: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.064136

DOI: 10.1103/PhysRevE.104.064136

Authors: Beatrice Ellerhoff and Kira Rehfeld

Contact: beatrice.ellerhoff(at)iup.uni-heidelberg.de

Please see ./license.md for terms of use. This github repository contains the maintained code and pre-processed data to create the figures of Ellerhoff and Rehfeld (2021). The raw data is available on Zenodo (doi: 10.5281/zenodo.5923109), together with the code to generate the pre-processed data. It is therefore important to note, that the github repository's subfolder (./processing) is not complete. In case you'd like to reproduce the data in ./data please follow the instructions in ./processing/readme_processing.md and download the input data from our archive at Zenodo. All figure can be reproduced using the post-processed data (./data) and the code in the github repository.

Organisation of this repository

The repository contains scripts (e.g., F2.R), input data (data), auxillarly files (helpers), and information (e.g., license.md). To reproduce a figure from Ellerhoff and Rehfeld (2021) run the script that is named as the figure (containing its number). Figure X of the main manuscript is denoted by FX.R and Figure X of the supplementary materials is denoted by FSX.R. In some cases (e.g. F3_and_FS11.R) it was convenient to create several figures together as they build on similar input data. However, sections in the code are marked with #FX, so that the individual figures can be also be created from these scripts.

scripts description
F2.R- F6.R Scripts to reproduce the figures of the main manuscript.
FS1.R- FS16.R Scripts to reproduce the figures of the supplementary material.
directories description
./data/ Contains the pre-processed data that serves as input for all figures. The sub-directory ./data/supp contains data used for supplementary figures only. ./data/shapes/50m_physical provides mapping information such as coastlines etc. from naturalearthdata, see ne_50m_land.README.html.
./helpers/ Contains scripts (.R-files) that define useful functions, initial parameters and load required packages, and meta data (.Rds files).
./processing/ Contains scripts (.R-files) to generate the data in ./data/. The input data (i.e. cleaned-up and preprocessed raw data) is contained in the accompanied Zenodo zip file. To reproduce all figures, this folder is not needed. However, to understand and reproduce the analysis, the scripts might be helpful.
additional files description
.gitignore Information for GIT version control to not add several file extensions to version control (e.g. *.png, *.pdf)
license.md/ license.html Licensing information
readme.md General README

Prerequisites

Our code requires the following R packages (loaded in ./helpers/init.R):

  • dplyr
  • tibble
  • tidyr
  • zoo
  • RColorBrewer
  • ggplot2
  • latex2exp
  • tseries
  • purrr
  • PaleoSpec (can be obtained from https://github.com/EarthSystemDiagnostics/paleospec, using devtools::install_github())

Creating some of the figures additionally requires (separately loaded in the corresponding .R scripts):

Generating some of the pre-processed data in ./processing (using data from Zenodo) might further require:

  • ncdf4
  • foreach
  • poweRlaw
  • VGAM
  • R.matlab
  • doParallel
  • furrr
  • Palinsol
  • rlist
  • fields

Data references

This manuscript is based upon data provided by the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP and PMIP. We give detailed information on all datasets considered in the supplementary materials of Ellerhoff and Rehfeld (2021). We thank the research groups for producing and making available their data from model outputs, measurements, paleoclimate, and forcing reconstructions.

Model simulations were obtained from:

  • Y. Zhong et al., Asymmetric Cooling of the Atlantic and Pacific Arctic During the Past Two Millennia: A Dual Observation-Modeling Study, Geophysical Research Letters (2018)
  • B. L. Otto-Bliesner et al., Climate variability and change since 850 ce an ensemble approach with the community earth system model, Bulletin of the American Meteorological Society (2016)
  • J. H. Jungclaus et al., Climate and carbon-cycle variability over the last millennium, Climate of the Past (2010)
  • J. C. Bühler et al., Comparison of the oxygen isotope signatures in speleothem records and iHadCM3 model simulations for the last millennium, Climate of the Past (2021)
  • P. Braconnot et al., Strengths and challenges for transient Mid76 to Late Holocene simulations with dynamical vegetation, Climate of the Past (2019)
  • Z. Liu, Transient simulation of last deglaciation with a new mechanism for Bølling–Allerød warming, Science (2009)
  • N. Fischer and J. H. Jungclaus, Evolution of the seasonal temperature cycle in a transient Holocene simulation: Orbital forcing and sea-ice, Climate of the Past (2011)

Paleoclimate, observational and reanalysis data:

  • H. Hersbach et al., The ERA5 global reanalysis, Quarterly Journal of the Royal Meteorological Society (2020)
  • C. P. Morice et al., Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: The HadCRUT4 data set, Journal of Geophysical Research Atmospheres (2012)
  • PAGES 2k Consortium, A global multiproxy database for temperature reconstructions of the Common Era, Scientific Data (2017)
  • PAGES 2k Consortium, Consistent multidecadal variability in global temperature reconstruc50 tions and simulations over the Common Era, Nature Geoscience (2019)

Forcing reconstructions:

  • G. A. Schmidt et al., Climate forcing reconstructions for use in PMIP simulations of the Last Millennium (v1.1), Geoscientific Model Development (2012)
  • T. J. Crowley and M. B. Unterman, Technical details concerning development of a 1200 yr proxy index for global volcanism, Earth System Science Data (2013)
  • C. Gao et al., Volcanic forcing of climate over the past 1500 years: An improved ice core-based index for climate models, Journal of Geophysical Research: At98 mospheres 113, 10.1029/2008JD010239 (2008).
  • M. Toohey and M. Sigl, Reconstructed volcanic stratospheric sulfur injections and aerosol optical depth, 500 BCE to 1900 CE, version 2, World Data Center for Climate (WDCC) at DKRZ (2017)
  • G. Delaygue and E. Bard, An Antarctic view of Beryllium-10 and solar activity for the past millennium, Climate Dynamics (2011)
  • R. Muscheler et al., Solar activity during the last 1000yr inferred from radionuclide records, Quaternary Science Reviews (2007)
  • F. Steinhilber et al., Total solar irradiance during the Holocene, Geophysical Research Letters (2009)
  • L. E. Vieira and S. K. Solanki, Evolution of the solar magnetic flux on time scales of years to millenia, Astronomy and Astrophysics (2010)
  • N. A. Krivova et al., Reconstruction of solar total irradiance since 1700 from the surface magnetic flux, Astronomy and Astrophysics (2007)
  • Y. Wang et al., Modeling the Sun’s Magnetic Field and Irradiance since 1713, The Astrophysical Journal (2005)
  • C. Fröhlich, Solar irradiance variability since 1978: Revision of the PMOD composite during solar cycle 21, Space Science Reviews (2006)
  • C. D. Keeling et al., Atmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii, TELLUS (1976)
  • A. L. Berger, Long-term variations of daily insolation and Quaternary climatic changes, Journal of Atmospheric Sciences (1978)
  • To numerically compute orbital variations based on Berger (1978), we used the Palinsol package from M. Crucifix (2016)

We acknowledge the R Core team and all package developers of packages used in this study. We thank them for their time and dedication to provide R and the packages to the public. Please see citation() for details on the R Core Team and citation("pkgname") for details on the developers of individual packages.

The study Ellerhoff and Rehfeld (2021) has been funded by the Heidelberg Graduate School for Physics, by the PalMod project (subProject no. 01LP1926C), and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Project No. 395588486. It benefited from discussions within the CVAS working group, a working group of the Past Global Changes (PAGES) project. We also thank the members of the Earth's climate and environmental dynamics and the Climatology and the Biosphere working groups for their helpful tips on preparing the analysis, code, and manuscript.

Please report bugs to beatrice.ellerhoff(at)iup.uni-heidelberg.de.

The authors, January 2022

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Code to reproduce the figures of https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.064136 (Ellerhoff and Rehfeld, 2021)

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