HR: 14:20h
AN: U23A-02    [Abstracts]
TI: A 2100-Year Reconstruction of July Rainfall Over Westcentral New Mexico
AU: * Stahle, D
EM: dstahle@uark.edu
AF: Department of Geosciences, University of Arkansas, Fayetteville, AR 72701, United States
AU: Cleaveland, M
EM: mcleavel@uark.edu
AF: Department of Geosciences, University of Arkansas, Fayetteville, AR 72701, United States
AU: Therrell, M
EM: therrell@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, United States
AU: Grissino-Mayer, H
EM: grissino@utk.edu
AF: Department of Geography, University of Tennessee, Knoxville, TN 37996, United States
AU: Griffin, D
EM: rdgriff@uark.edu
AF: Department of Geosciences, University of Arkansas, Fayetteville, AR 72701, United States
AU: Fye, F
EM: ffye@uark.edu
AF: Department of Geosciences, University of Arkansas, Fayetteville, AR 72701, United States
AB: We have developed a new 2,141-year long tree-ring chronology of latewood (LW) width from ancient Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosae) at El Malpais National Monument, New Mexico. This is one of the longest precipitation-sensitive tree-ring chronologies yet constructed for the American Southwest and has been used to develop the first continuous multi-millennial tree-ring reconstruction of July precipitation in the region of the North American Monsoon System (NAMS). Monthly average precipitation increases sharply in July over western New Mexico, marking the dramatic onset to the summer monsoon season. The LW chronology explains 44 percent of the interannual variability of July precipitation in the instrumental record for New Mexico climate divisions 1 and 4 (1960-2004), after removal of the linear dependence of LW width on earlywood width following Meko and Baisan (2001), and has passed statistical tests of verification on independent July precipitation data (1895-1959). The instrumental and tree-ring reconstructed July precipitation data are correlated with the concurrent 500 mb height field over western North America and with the sea surface temperature gradient from the central to eastern North Pacific. The reconstruction exhibits several severe sustained July droughts that exceed any witnessed during the instrumental era, and has significant spectral power at periods near 3-5, 20, and 70 years.
DE: 1812 Drought
DE: 1854 Precipitation (3354)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4920 Dendrochronology
SC: Union [U]
MN: 2007 Joint Assembly