North Atlantic Oscillation Index Coral Sr/Ca 218 Year Reconstruction Goodkin, N.F.; Hughen, K.A.; Doney, S.C.; Curry, W.B. Goodkin, N.F. Hughen, K.A. Doney, S.C. Curry, W.B. Atmospheric and Oceanic Circulation Patterns Reconstruction North Atlantic Oscillation earth science/paleoclimate/climate reconstructions|corals and sclerosponges (North Atlantic Oscillation Index,strontium/calcium,null,standard deviation unit,null,climate reconstructions|corals and sclerosponges,filtered,null,N,3-5yrIndex) earth science/paleoclimate/climate reconstructions|corals and sclerosponges (North Atlantic Oscillation Index,strontium/calcium,null,standard deviation unit,null,climate reconstructions|corals and sclerosponges,filtered,null,N,combined) earth science/paleoclimate/climate reconstructions|corals and sclerosponges (age,null,null,year Common Era,null,climate reconstructions|corals and sclerosponges,null,null,N,null) earth science/paleoclimate/climate reconstructions|corals and sclerosponges (North Atlantic Oscillation Index,strontium/calcium,null,standard deviation unit,null,climate reconstructions|corals and sclerosponges,filtered,null,N,20-100yr Index) earth science/paleoclimate/reconstructions (Bermuda>LATITUDE 32>LONGITUDE -64) The North Atlantic Oscillation is a meridional oscillation of atmospheric mass measured between Iceland and the Azores, which drives winter climate variability in eastern North America and Europe. A prolonged period of the positive phase during the 1990s led to the suggestion that anthropogenic warming was affecting the behaviour of the North Atlantic Oscillation. However, instrumental records are too short to compare observations during periods of extended warm and cold hemispheric temperatures, and existing palaeoclimate reconstructions primarily capture terrestrial variability. Here we present a record of Sr/Ca, a sea surface temperature proxy, from a Bermuda coral from 1781 to 1999. We use this monthly resolved record to reconstruct past variability of the North Atlantic Oscillation at multiple frequencies. Our record shows enhanced multidecadal scale variability during the late twentieth century compared with the end of the Little Ice Age (1800-1850). We suggest that variability within the North Atlantic Oscillation is linked to the mean temperature of the Northern Hemisphere, which must be considered in any long-term predictions. STUDY NOTES: North Atlantic Oscillation Index (NAO) reconstruction based on winter coral strontium-to-calcium ratio, a proxy for winter SST. The SST-based, multifrequency reconstruction of the NAO extends back to the end of the Little Ice Age (LIA). It is the first non-terrestrial reconstruction showing long-term multidecadal behaviour of the NAO. Coral Sr/Ca was used to reconstruct the NAO by filtering the Sr/Ca record to isolate the two frequency bands where the coral data are coherent with the NAO. To evaluate this approach, the same process was applied to instrumental SST and NAO data. The 3-5 year coherence is 0.40 (95% significant, n effective = 124) and the 20-100 year coherence is -0.47 (95% significant, n effective = 24), both with the expected phase relationship. These results agree well with those found for the Sr/Ca and instrumental NAO. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Goodkin, N.F. Investigator : Hughen, K.A. Investigator : Doney, S.C. Investigator : Curry, W.B. 2010-11-15 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/9812 https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.txt https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.xls https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.txt https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.xls English https://www.ncdc.noaa.gov/paleo/study/9812 https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.txt https://www1.ncdc.noaa.gov/pub/data/paleo/coral/atlantic/goodkin2010nao.xls Goodkin, N.F., K.A. Hughen, S.C. Doney, and W.B. Curry. 2008. Increased multidecadal variability of the North Atlantic Oscillation since 1781. Nature Geoscience, Vol. 1, pp. 844-847, December 2008. Published online: 9 November 2008, doi:10.1038/ngeo352 START YEAR: 1781 AD * END YEAR: 1988 AD -64 32 -64 32