Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
doi:10.5194/cp-2016-98
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Oct 2016
Review status
A revision of this discussion paper is under review for the journal Climate of the Past (CP).
Testing the analog method in reconstructing the global mean annual temperature during the Common Era
Juan José Gómez-Navarro1,2,3, Eduardo Zorita4, Christoph C. Raible1,2, and Raphael Neukom2,5 1Climate and Environmental Physics, Physics Institute, University of Bern, Switzerland
2Oeschger Centre for Climate Change Research, University of Bern, Switzerland
3Department of Physics, University of Murcia, Spain
4Institute of Coastal Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
5Institute of Geography, University of Bern, Switzerland
Abstract. This study addresses the possibility to carry out global gridded mean annual temperature reconstructions using a worldwide network of proxy records and a method based on the search of analogs (AM-CFR). Several variants of the method are evaluated, and their performance is analysed. As test bed for the reconstruction, the PAGES2K proxy database (version 1.9.0) is employed as predictor, the HadCRUT4 dataset is the set of observations used as predictand and target, and a set of simulations from the PMIP3 are used as pool to draw analogs and carry out Pseudo Proxy Experiments (PPE). The performance of the variants of the analog method is evaluated through a series of PPEs in growing complexity, from a perfect scenario to a realistic one where the pseudo-proxy records are contaminated with noise and missing values mimicking the limitations of actual proxies. From all the tests carried out, we can conclude that the analog pool provided by PMIP3 ensemble is large enough to reconstruct global annual temperatures during the Common Era. Further, the search of analogs based on a metric that minimises the RMSE outperforms other evaluated metrics, including the search of analogs in the range-reduced space expanded by the leading EOFs. We show how the method is able to extrapolate the information of the proxy network to produce a homogeneous gap-free climate field reconstruction with valuable information in areas barely covered by proxies. Finally, the method is applied to reconstruct the HadCRUT4 observed temperature based on the calibration of the proxies. The reconstructed fields reproduce the observed decadal temperature variability. The AM-CFR is a suitable tool which is able to deliver valuable climate field reconstructions for the Common Era.

Citation: Gómez-Navarro, J. J., Zorita, E., Raible, C. C., and Neukom, R.: Testing the analog method in reconstructing the global mean annual temperature during the Common Era, Clim. Past Discuss., doi:10.5194/cp-2016-98, in review, 2016.
Juan José Gómez-Navarro et al.
Juan José Gómez-Navarro et al.
Juan José Gómez-Navarro et al.

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