North American Monsoon 470-Year Subannual Precipitation Index Reconstructions Griffin, D.; Woodhouse, C.A.; Meko, D.M.; Stahle, D.W.; Faulstich, H.L.; Carrillo, C.; Touchan, R.; Castro, C.L.; Leavitt, S.W. Griffin, D. Woodhouse, C.A. Meko, D.M. Stahle, D.W. Faulstich, H.L. Carrillo, C. Touchan, R. Castro, C.L. Leavitt, S.W. Monsoon Precipitation Reconstruction precipitation 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/instrumental (precipitation,null,null,standard deviation unit,Oct-Apr,instrumental,null,null,N,null) earth science/paleoclimate/instrumental (precipitation,null,null,standard deviation unit,Jun-Aug,instrumental,null,null,N,null) earth science/paleoclimate/climate reconstructions|tree ring (precipitation,ring width,null,standard deviation unit,Oct-Apr,climate reconstructions|tree ring,null,null,N,based on latewood width) earth science/paleoclimate/climate reconstructions|tree ring (precipitation,ring width,null,standard deviation unit,Jun-Aug,climate reconstructions|tree ring,null,null,N,based on latewood width) earth science/paleoclimate/reconstructions (North American Monsoon Experiment Region 2>LATITUDE >LONGITUDE ) The North American monsoon is a major focus of modern and paleoclimate research, but relatively little is known about interannual- to decadal-scale monsoon moisture variability in the pre-instrumental era. This study draws from a new network of subannual tree-ring latewood width chronologies and presents a 470-year reconstruction of monsoon (June-August) standardized precipitation for southwestern North America. Comparison with an independent reconstruction of cool-season (October-April) standardized precipitation indicates that southwestern decadal droughts of the last five centuries were characterized not only by cool-season precipitation deficits but also by concurrent failure of the summer monsoon. Monsoon drought events identified in the past were more severe and persistent than any of the instrumental era. The relationship between winter and summer precipitation is weak, at best, and not time stable. Years with opposing-sign seasonal precipitation anomalies, as noted by other studies, were anomalously frequent during the mid to late 20th century. STUDY NOTES: Southwestern North America monsoon (June-August) precipitation reconstruction, based on a multispecies tree ring latewood width chronology network. Target region for the reconstructions is monsoon region 2 (NAM2), as defined by the North American Monsoon Experiment Forecast Forum (30-35N, 107.75-113.25W). Monthly precipitation data are from a 0.5 degree gridded product developed by NOAA. NAM2 grid point data were averaged to produce time series of monthly precipitation and correlation analysis was used to assess relationships to the subannual tree-ring chronologies. October-April (cool season) and June-August (monsoon) were selected as the seasons for reconstruction, and precipitation totals for these seasons were converted to standardized precipitation indices (SPI). NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Griffin, D. Investigator : Woodhouse, C.A. Investigator : Meko, D.M. Investigator : Stahle, D.W. Investigator : Faulstich, H.L. Investigator : Carrillo, C. Investigator : Touchan, R. Investigator : Castro, C.L. Investigator : Leavitt, S.W. 2013-04-16 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/14248 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/nam2precip2013.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/nam2precip2013.txt English https://www.ncdc.noaa.gov/paleo/study/14248 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/nam2precip2013.txt Daniel Griffin, Connie A. Woodhouse, David M. Meko, David W. Stahle, Holly L. Faulstich, Carlos Carrillo, Ramzi Touchan, Christopher L. Castro, and Steven W. Leavitt. 2013. North American monsoon precipitation reconstructed from tree-ring latewood. Geophysical Research Letters, Vol. 40. DOI: 10.1002/grl.50184 START YEAR: 1530 AD * END YEAR: 2008 AD -113.25 30 -107.75 35