Patterns and Sources of Multidecadal Oscillations in Drought-Sensitive Tree-Ring Records from the Central and Southern Rocky Mountains

• Published in: Geophysical Research Letters
• Main Authors: Gray, S. T., Betancourt, J. L., Fastie, C. L., Jackson, Stephen T.
• Format: Other Non-Article Part of Journal/Newspaper
• Language: English
• Published: University of Wyoming. Libraries 2003
• Subjects: drought; tree-rings; multi decadal variability; Pacific Decadal Oscillation; Atlantic Multidecadal Oscillation; Botany; Pacific; North Atlantic
• Online Access: https://hdl.handle.net/20.500.11919/759; https://doi.org/10.1029/2002GL016154

Tree-ring records spanning the past seven centuries from the central and southern Rocky Mountains were studied using wavelet analysis to examine multidecadal (>30-70 yr) patterns of drought variation. Fifteen tree-ring series were grouped into five regional composite chronologies based on shared low-frequency behavior. Strong multidecadal phasing of moisture variation was present in all regions during the late 16th century megadrought. Oscillatory modes in the 30-70 yr domain persisted until the mid-19th century in two regions, and wet-dry cycles were apparently synchronous at some sites until the 1950s drought. The 16th/17th century pattern of severe multidecadal drought followed by decades of wet conditions resembles the 1950s drought and post-1976 wet period. The 16th century megadrought, which may have resulted from coupling of a decadal (similar to 20-30 yr) Pacific cool phase with a multidecadal warm phase in the North Atlantic, marked a substantial reorganization of climate in the Rocky Mountain region.