2000 Year Precipitation-Based Southern Oscillation Index Reconstruction Yan, H.; Sun, L.; Wang, Y.; Huang, W.; Qiu, S.; Yang, C. Yan, H. Sun, L. Wang, Y. Huang, W. Qiu, S. Yang, C. Atmospheric and Oceanic Circulation Patterns Reconstruction ENSO earth science/paleoclimate/climate reconstructions|paleoceanography|paleolimnology (age,null,null,year Common Era,null,climate reconstructions|paleoceanography|paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleoceanography|paleolimnology (Southern Oscillation Index,null,null,standard deviation unit,null,climate reconstructions|paleoceanography|paleolimnology,interpolated,null,N,resampled for uniform temporal spacing) earth science/paleoclimate/reconstructions (Global>LATITUDE >LONGITUDE ) The El Niño-Southern Oscillation (ENSO) is a coupled ocean-atmosphere climate phenomenon in the tropical Pacific Ocean. The interannual climate variations have been shown to modify both the Hadley and Walker meridional and zonal atmospheric circulations, with strong impacts on global climate. Proxy-based reconstructions of the Southern Oscillation Index on a multi-decadal scale have shown that the strength and frequency of El Niño occurrences have varied over the past millennium. Here we compile reconstructions of precipitation from regions that experience substantial ENSO variability to extend the multidecadal-scale Southern Oscillation Index to include the past 2,000 years. We find that the Medieval Warm Period (~AD 800–1300) was characterized by a negative index, which indicates more El Niño-dominated conditions, whereas during the Little Ice Age (~AD 1400-1850) more La Niña-dominated conditions prevailed. The Southern Oscillation Index we derive is significantly correlated with reconstructions of solar irradiance STUDY NOTES: Reconstruction of a precipitation-based Southern Oscillation Index (SOIpr) for the past 2000 years. The Southern Oscillation Index (SOI) is positively correlated with precipitation over the Indo-Pacific warm pool, and negatively correlated with precipitation over the eastern and mid-tropical Pacific. Based on this correlation between SOI and precipitation, we propose a novel and SOI-like index, SOIpr, as the difference between normalized annual rainfalls in the positive rainfall anomaly area (PA) of the tropical western Pacific, and the negative rainfall anomaly area (NA) of the equatorial eastern and mid-Pacific. Proxy precipitation records from Indonesia and Galapagos were used to calculate SOIpr for the past two millennia. The Indonesian rainfall was derived from a salinity reconstruction based on planktonic-foraminifera d18O and the Mg/Ca ratio (Oppo et al. 2009). Data available from WDC Paleo at: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ oppo2009/oppo2009.txt The rainfall history of the Galapagos (7241 BC - AD 2004) is derived from a lake level reconstruction which is based on the grain size data from the Lago El Junco sediment core (Conroy et al. 2008). Data available from WDC Paleo at: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/paleolimnology/ southamerica/ecuador/galapagos/eljunco2008.txt NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Yan, H. Investigator : Sun, L. Investigator : Wang, Y. Investigator : Huang, W. Investigator : Qiu, S. Investigator : Yang, C. 2011-10-07 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/12203 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.xls English https://www.ncdc.noaa.gov/paleo/study/12203 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yan2011/yan2011soipr.xls Yan, H., L. Sun, Y. Wang, W. Huang, S. Qiu, and C. Yang. A record of the Southern Oscillation Index for the past 2,000 years from precipitation proxies. Nature Geoscience, DOI: 10.1038/NGEO1231 START YEAR: 50 AD * END YEAR: 1955 AD -180 -90 180 90