A pollen-based reconstruction of summer temperature in central North America and implications for circulation patterns during medieval times

noaa-recon-17133 Upper Midwest USA Last Millennium Summer 2m Air Temperature Wahl, E.R.; Diaz, H.F.; Ohlwein, C. Upper Midwest USA Last Millennium Summer 2m Air Temperature 2014-09-02 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/17133 Investigator E.R. Wahl Investigator H.F. Diaz Investigator C. Ohlwein earth science paleoclimate climate reconstructions|pollen age,null,null,year Common Era,null,climate reconstructions|pollen,null,null,N,null earth science paleoclimate climate reconstructions|pollen surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,1st percentile; logistic generalized linear model; 2m air temperature earth science paleoclimate climate reconstructions|pollen surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,50th percentile; logistic generalized linear model; 2m air temperature earth science paleoclimate climate reconstructions|pollen surface air temperature,null,percentile,degree Celsius,summer,climate reconstructions|pollen,null,regression analysis,N,99th percentile; logistic generalized linear model; 2m air temperature earth science paleoclimate reconstructions air temperature geoscientificInformation Air Temperature Reconstruction Medieval Climate Anomaly (MCA) North Atlantic Oscillation 1045 AD 1965 AD 905 cal yr BP -15 cal yr BP Complete 45.26667 45.28333 -91.48333 -91.45834 330 335 Continent North America United States Of America Wisconsin Dark Lake (DARKLAKE)>LATITUDE 45.275>LONGITUDE -91.475 Continent North America United States Of America Wisconsin Little Pine Lake (LITTLPIN)>LATITUDE 45.28333>LONGITUDE -91.48333 Continent North America United States Of America Wisconsin Ruby Lake (RUBYLAKE)>LATITUDE 45.26667>LONGITUDE -91.45834 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 Wahl, E., H. Diaz, and C. Ohlwein 2012 A pollen-based reconstruction of summer temperature in central North America and implications for circulation patterns during medieval times Global and Planetary Change 84-85 66-74 10.1016/j.gloplacha.2011.10.005

We present a reconstruction of mean summer temperature for the northern Midwest of theUSA based on lacustrine pollen records from three different lakes in Wisconsin. The results suggest a relatively warm period during the earlier part of the record (~1200–1500 CE) followed by a cooler Little Ice Age (~1500–1900) and a subsequent warming to modern conditions. The reconstructed modern summer mean temperature is in good agreement with observations, and the decades of the 1930s to 1950s appear to be the warmest such period in the proxy record (through 1974). Analyses of circulation features associated with the warmest summers in the recent climate record suggest a prevalence of continental ridging accompanied by generally dry conditions during these warm summers in the Midwest. Drought reconstruction using the Palmer Drought Severity Index (PDSI) and tree-ring records as predictors also yield relatively dry conditions in medieval times for the central US. As reported in a number of recent studies, possible forcing mechanisms include La Niña-like conditions in the equatorial Pacific and warmer than average waters in the tropical Indo-western Pacific Ocean possibly coupled to a positive mode of the AMO/ NAO North Atlantic circulation pattern. STUDY NOTES: Fossil pollen from three lakes in Wisconsin USA are used (Dark Lake, Ruby Lake, Little Pine Lake) along with modern pollen-climate relationships from the North American Pollen Data Base

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-darklake.txt Formatted Text File; Dark Lake Reconstruction GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt Original Source URL; Pollen Data GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-littlepine.txt Formatted Text File; Little Pine Lake Reconstruction GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/reconstructions/wahl2012/wahl2012-rubylake.txt Formatted Text File; Ruby Lake Reconstruction USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11