noaa-recon-26810 Winter North Atlantic Oscillation Index Reconstruction from Tree-Rings since 910 C.E. Cook, E.R.; Kushnir, Y.; Smerdon, J.E.; Williams, A.P.; Anchukaitis, K.J.; Wahl, E.R. Winter North Atlantic Oscillation Index Reconstruction from Tree-Rings since 910 C.E. 2019-05-14 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/26810 Investigator E.R. Cook Investigator Y. Kushnir Investigator J.E. Smerdon Investigator A.P. Williams Investigator K.J. Anchukaitis Investigator E.R. Wahl earth science paleoclimate reconstructions atmospheric circulation geoscientificInformation Atmospheric and Oceanic Circulation Patterns Reconstruction 910 AD 2018 AD 1040 cal yr BP -68 cal yr BP Complete 38 65 -50 -10 Ocean Atlantic Ocean North Atlantic Ocean North Atlantic Oscillation>LATITUDE >LONGITUDE None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Cook, Edward R., Yochanan Kushnir, Jason E. Smerdon, A. Park Williams, Kevin J. Anchukaitis, and Eugene R. Wahl 2019 Climate Dynamics 10.1007/s00382-019-04696-2 Jones, P. , Davies, T. , Lister, D. , Slonosky, V. , Jónsson, T., Bärring, L., Jönsson, P. , Maheras, P. , Kolyva-Machera, F. , Barriendos, M. , Martin-Vide, J. , Rodriguez, R. , Alcoforado, M. , Wanner, H. , Pfister, C. , Luterbacher, J. , Rickli, R. , Schuepbach, E. , Kaas, E. , Schmith, T. , Jacobeit, J. and Beck, C. 1999 International Journal of Climatology 10.1002/(SICI)1097-0088(19990330)19:4<347::AID-JOC363>3.0.CO

We develop a new reconstruction of the winter North Atlantic Oscillation (NAO) index using a network of 97 Euro-Mediterranean tree-ring series. The reconstruction covers the period 910-2018 C.E., making it the longest annually resolved estimate of winter NAO variability available. We use nested correlation-weighted principal components regression and the Maximum Entropy Bootstrap method to generate a 2400-member ensemble of reconstructions for estimating the final reconstruction and its quantile uncertainties. Extensive validation testing of the new reconstruction against data withheld from the calibration exercise demonstrates its skill. The skill level of the new reconstruction is also an improvement over two NAO reconstructions published earlier. Spectral analyses indicate that the new reconstruction behaves like a "white noise" process with intermittent band-limited power, suggesting that the winter NAO is stochastically forced. The "white noise" properties of our reconstruction are also shown to be consistent with the spectral properties of long instrumental NAO indices extending back to 1781 and NAO indices extracted from a large number of forced climate model runs covering the last millennium. In contrast, an annually resolved multi-proxy NAO reconstruction of comparable length, based in part on speleothem data, behaves more like externally forced "red noise" process, which is inconsistent with our reconstruction, long observations, and forced model runs. STUDY NOTES: In the NAO reconstruction data table, -05%CL is an amount to be subtracted from the median and +95%CL is an amount to be added to the median.

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/cook2019/cook2019-ensemble.txt NOAA Template File; NAO Reconstruction Ensemble Members GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/cook2019/cook2019-nao.txt NOAA Template File; NAO Reconstruction Data USA/NOAA DIF Version 9.8.4 2019-05-21 2019-05-21