noaa-recon-19119 The "Living Blended Drought Atlas (LBDA)" North American Drought Reconstruction for the last 2000 years Cook, E.R.; Seager, R.; Heim, R.R.; Vose, R.S.; Herweijer, C.; Woodhouse, C.A. The "Living Blended Drought Atlas (LBDA)" North American Drought Reconstruction for the last 2000 years 2015-07-29 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/19119 Investigator E.R. Cook Investigator R. Seager Investigator R.R. Heim Investigator R.S. Vose Investigator C. Herweijer Investigator C.A. Woodhouse earth science paleoclimate climate reconstructions|tree ring age,null,null,year Common Era,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring sample identification,null,null,null,null,climate reconstructions|tree ring,null,null,N,gridpoint number earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,null,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,verification coefficient of determination,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate instrumental Palmer Modified Drought Index,null,null,dimensionless,null,instrumental,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,verification reduction of error,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,verification root mean square error,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,calibration leave-one-out cross-validation reduction of error,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring latitude,null,null,degree north,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring longitude,null,null,degree east,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,verification coefficient of efficiency,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate climate reconstructions|tree ring Palmer Modified Drought Index,null,calibration coefficient of determination,dimensionless,null,climate reconstructions|tree ring,null,null,N,null earth science paleoclimate reconstructions precipitation geoscientificInformation Palmer Drought Index Reconstruction 0 AD 2005 AD 1950 cal yr BP -55 cal yr BP Complete 9 72 -170 -50 Continent North America North America and northern Central America>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, E.R., Seager, R., Heim, R.R., Vose, R.S., Herweijer, C., and Woodhouse, C. 2010 Journal of Quaternary Science 25 1 48-61 10.1002/jqs.1303

IPCC Assessment Report 4 model projections suggest that the subtropical dry zones of the world will both dry and expand poleward in the future due to greenhouse warming. The US Southwest is particularly vulnerable in this regard and model projections indicate a progressive drying there out to the end of the 21st century. At the same time, the USA has been in a state of drought over much of the West for about 10 years now. While severe, this turn of the century drought has not yet clearly exceeded the severity of two exceptional droughts in the 20th century. So while the coincidence between the turn of the century drought and projected drying in the Southwest is cause for concern, it is premature to claim that the model projections are correct. At the same time, great new insights into past drought variability over North America have been made through the development of the North American Drought Atlas from tree rings. Analyses of this drought atlas have revealed past megadroughts of unprecedented duration in the West, largely in the Medieval period about 1000 years ago. A vastly improved Living Blended Drought Atlas (LBDA) for North America now under develop- ment reveals these megadroughts in far greater detail. The LBDA indicates the occurrence of the same Medieval megadroughts in the West and similar-scale megadroughts in the agriculturally and commercially important Mississippi Valley. Possible causes of these megadroughts and their implications for the future are discussed. STUDY NOTES: A high-resolution North American drought atlas reconstructed from tree rings Provided Keywords: North American drought, tree rings, megadroughts, pluvials, PDSI

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/drought/LBDA2010/LBDA_PMDI_JJA_Recons_cal:ver_stats.txt Text File; Reconstructed PMDI calibration/verification statistics GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/drought/LBDA2010/LBDA_PMDI_JJA_Recons.txt Text File; Reconstructed PMDI - one column per grid point GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/drought/LBDA2010/LBDA_PMDI_Instrumental_data.txt Text File; Instrumental PMDI data used for calibration/verification GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/drought/LBDA2010/LBDA_PMDI_Instrumental_metadata.txt Text File; Instrumental PMDI metadata - one line per grid point data set GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/drought/LBDA2010/nada_hd2_cl.nc netCDF File; LBDA data USA/NOAA DIF Version 9.8.4 2019-05-17 2019-05-17