Data & code repository for "A re-appraisal of the ENSO response to volcanism with paleoclimate data assimilation"

This repository includes the data and code that can be used to reproduce the figures for the paper entitled A re-appraisal of the ENSO response to volcanism with paleoclimate data assimilation (DOI: 10.1038/s41467-022-28210-1).

The code is tested with Python v3.8, and the package LMRt (Zhu et. al., 2021) is required to perform essential analysis (e.g. Superposed Epoch Analysis) and the corresponding visualization.

Repository Structure

• recons: the folder that includes our reconstructions of (i) the NINO3.4 series with 0.05, 0.25, 0.5, 0.75, 0.95 quantiles and (ii) the ensemble median surface temperature field

  • recon_Ocn2kCorals_Li13b6.nc: the reconstruction that assimilates all the available Ocean2k corals (Tierney et al., 2015; PAGES2k Consortium, 2017) and the six best ENSO predictors in Li et al. (2013).
  • recon_Corals_Li13b6.nc: the reconstruction that assimilates the corals reaching back before 1750 CE and the six best ENSO predictors in Li et al. (2013).
  • recon_Corals.nc: the reconstruction that assimilates the corals reaching back before 1750 CE.
  • recon_Li13b6.nc: the reconstruction that assimilates the six best ENSO predictors in Li et al. (2013).

• notebooks: the folder that includes Jupyter notebooks

  • Fig-1.ipynb: the notebook that performs analysis and generates Fig. 1 in the main text
  • Fig-2.ipynb: the notebook that performs analysis and generates Fig. 2 in the main text
  • Fig-3.ipynb: the notebook that performs analysis and generates Fig. 3 in the main text
  • Fig-4.ipynb: the notebook that performs analysis and generates Fig. 4 in the main text

• data: the folder that includes auxiliary data for the analysis and visualization

  • proxy_locs.pkl: the pickle file that includes the location information of the assimilated proxies
  • eVolv2k_v3_ds_1.nc: the eVolv2k v3 volcanic forcing data (Toohey & Sigl, 2017), which is publicly available and can be downloaded here
  • palmyra2013.txt: the Palmyra coral d18O data (Emile-Geay et al., 2013), which is publicly available and can be downloaded here
  • Li13b6.txt: the six best ENSO predictors in Li et al. (2013), including the first two principle components (PCs) of the North American Drought Atlas (NADA; Cook et al., 2004) and Monsoon Asia Drought Atlas (MADA; Cook et al., 2010) networks, the Kauri tree-ring composite (Fowler et al., 2012), and the South America Altiplano (SA Altiplano) tree-ring composite (Morales et al., 2012)
  • enso-li2013.txt: the Li et al. (2013) NINO3.4 reconstruction, which is publicly available and can be downloaded with the link: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/enso-li2013.txt
  • ERSSTv5_sst_DJF.nc: the ERSSTv5 boreal winter (December-February) SST field data (Huang et al., 2017)

• figs: the folder that includes figures

  • Fig-1.pdf: Fig. 1 in the main text
  • Fig-2.pdf: Fig. 2 in the main text
  • Fig-3.pdf: Fig. 3 in the main text
  • Fig-4.pdf: Fig. 4 in the main text

References

• Cook, E. R., Woodhouse, C. A., Eakin, C. M., Meko, D. M., & Stahle, D. W. (2004). Long-Term Aridity Changes in the Western United States. Science, 306(5698), 1015–1018. https://doi.org/10.1126/science.1102586
• Cook, E. R., Anchukaitis, K. J., Buckley, B. M., D’Arrigo, R. D., Jacoby, G. C., & Wright, W. E. (2010). Asian Monsoon Failure and Megadrought During the Last Millennium. Science, 328(5977), 486–489. https://doi.org/10.1126/science.1185188
• Emile-Geay, J., Cobb, K. M., Mann, M. E., & Wittenberg, A. T. (2013). Estimating Central Equatorial Pacific SST Variability over the Past Millennium. Part II: Reconstructions and Implications. Journal of Climate, 26(7), 2329–2352. https://doi.org/10.1175/JCLI-D-11-00511.1
• Fowler, A. M., Boswijk, G., Lorrey, A. M., Gergis, J., Pirie, M., McCloskey, S. P. J., et al. (2012). Multi-centennial tree-ring record of ENSO-related activity in New Zealand. Nature Climate Change, 2(3), 172–176. https://doi.org/10.1038/nclimate1374
• Huang, B., Thorne, P. W., Banzon, V. F., Boyer, T., Chepurin, G., Lawrimore, J. H., et al. (2017). Extended Reconstructed Sea Surface Temperature, Version 5 (ERSSTv5): Upgrades, Validations, and Intercomparisons. Journal of Climate, 30(20), 8179–8205. https://doi.org/10.1175/JCLI-D-16-0836.1
• Li, J., Xie, S.-P., Cook, E. R., Morales, M. S., Christie, D. A., Johnson, N. C., et al. (2013). El Niño modulations over the past seven centuries. Nature Climate Change, 3(9), 822–826. https://doi.org/10.1038/nclimate1936
• Morales, M. S., Christie, D. A., Villalba, R., Argollo, J., Pacajes, J., Silva, J. S., et al. (2012). Precipitation changes in the South American Altiplano since 1300 AD reconstructed by tree-rings. Climate of the Past, 8(2), 653–666. https://doi.org/10.5194/cp-8-653-2012
• PAGES2k Consortium (2017). A global multiproxy database for temperature reconstructions of the Common Era. Scientific Data, 4, 170088. https://doi.org/10.1038/sdata.2017.88
• Tierney, J. E., Abram, N. J., Anchukaitis, K. J., Evans, M. N., Giry, C., Kilbourne, K. H., et al. (2015). Tropical sea surface temperatures for the past four centuries reconstructed from coral archives. Paleoceanography, 30(3), 2014PA002717. https://doi.org/10.1002/2014PA002717
• Toohey, M., & Sigl, M. (2017). Volcanic stratospheric sulfur injections and aerosol optical depth from 500 BCE to 1900 CE. Earth System Science Data, 9(2), 809–831. https://doi.org/10.5194/essd-9-809-2017
• Zhu, F., Emile-Geay, J. Hakim, G. J., Tardif, R., and Perkins., A., (2021). LMR Turbo (LMRt): a lightweight implementation of the LMR framework (0.8.0). Zenodo. http://doi.org/10.5281/zenodo.5205223

How to cite this repo

This repo can be cited with DOI: 10.5281/zenodo.5716165.