DOI: 10.5281/zenodo.2579203
title: Data assimilation-based surface temperature reconstructions over the last two millennia over Antarctica

description: This dataset contains data assimilation-based temperature and δ<sup>18</sup>O reconstructions in 10 Antarctic regions over the last two millennia, presented in :


Klein, F., Abram, N. J., Curran, M. A. J., Goosse, H., Goursaud, S., Masson-Delmotte, V., Moy, A., Neukom, R., Orsi, A., Sjolte, J., Steiger, N., Stenni, B., and Werner, M.: Assessing the robustness of Antarctic temperature reconstructions over the past two millennia using pseudoproxy and data assimilation experiments, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-90, in review, 2018. 


We use a new database of stable oxygen isotopes in ice cores compiled in the framework of Antarctica2k (Stenni et al., 2017) to constrain model ensembles derived from two simulations: one performed using ECHAM5-MPI-OM that covers the period 800-1999 CE with a horizontal resolution of 3.75° by 3.75° (Sjolte et al., 2018), and the other performed with ECHAM5-wiso, spanning 1871-2011 CE at 1.125° spatial resolution (Steiger et al., 2017). This latter simulation is available here.

Four netCDF files are available:


	d18O_DA_ECHAM5-MPI-OM_1-2015.nc: data assimilation-based δ<sup>18</sup>O reconstructions using the model ensemble derived from ECHAM5-MPI-OM
	ts_DA_ECHAM5-MPI-OM_1-2015.nc: data assimilation-based surface temperature reconstructions using the model ensemble derived from ECHAM5-MPI-OM
	d18O_DA_ECHAM5-wiso_1-2015.nc: data assimilation-based δ<sup>18</sup>O reconstructions using the model ensemble derived from ECHAM5-wiso
	ts_DA_ECHAM5-wiso_1-2015.nc: data assimilation-based surface temperature reconstructions using the model ensemble derived from ECHAM5-wiso


The variables included in the NetCDF files are:


	region: integers from 1 to 10 corresponding to the ID of the ten reconstructions targets, that were defined in Stenni et al. (2017):
	
		1: East Antarctic Plateau
		2: Wilkes Land Coast
		3: Weddell Sea Coast
		4: Antarctic Peninsula
		5: West Antarctic Ice Sheet
		6: Victoria Land Coast-Ross Sea
		7: Dronning Maud Land Coast
		8: West Antarctica
		9: East Antarctica
		10: Antarctica
	
	
	time: integers from 1 to 2015, corresponding to the years CE covered by the reconstructions
	DA_ts (or DA_d18O): data assimilation-based reconstructed surface temperature (or δ<sup>18</sup>O). The values are annual means and are given in anomalies computed over full period. The units are degrees celsius (or permil). 
	DA_ts_std (or DA_d18O_std): Weighted standard deviation of the particles used for reconstructing temperature (or δ<sup>18</sup>O). The units are degrees celsius (or permil).


For a detailed description of the experimental design, please see the associated publication (Klein et al., 2018). Don't hesitate to contact François Klein for more information.

References

Klein, F., Abram, N. J., Curran, M. A. J., Goosse, H., Goursaud, S., Masson-Delmotte, V., Moy, A., Neukom, R., Orsi, A., Sjolte, J., Steiger, N., Stenni, B., and Werner, M.: Assessing the robustness of Antarctic temperature reconstructions over the past two millennia using pseudoproxy and data assimilation experiments, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-90, in review, 2018.

Sjolte, J., Sturm, C., Adolphi, F., Vinther, B. M., Werner, M., Lohmann, G., and Muscheler, R.: Solar and volcanic forcing of North Atlantic climate inferred from a process-based reconstruction, Climate of the Past, 14, 1179–1194, https://doi.org/10.5194/cp-14-1179-2018, 2018.

Steiger, N. J., Steig, E. J., Dee, S. G., Roe, G. H., and Hakim, G. J.: Climate reconstruction using data assimilation of water isotope ratios from ice cores, Journal of Geophysical Research: Atmospheres, 122, 1545–1568, https://doi.org/10.1002/2016JD026011, 2017.

Stenni, B., Curran, M. A. J., Abram, N. J., Orsi, A., Goursaud, S., Masson-Delmotte, V., Neukom, R., Goosse, H., Divine, D., van Ommen, T., Steig, E. J., Dixon, D. A., Thomas, E. R., Bertler, N. A. N., Isaksson, E., Ekaykin, A., Werner, M., and Frezzotti, M.: Antarctic climate variability on regional and continental scales over the last 2000 years, Climate of the Past, 13, 1609–1634, https://doi.org/10.5194/cp-13-1609-2017, 2017.