400+ Years of ENSO-like Climate Cyclicity from Tree Ring Width-Data, Wind River Range, Wyoming, USA.

Thursday, 18 December 2014
Dennis E Dahms, Derek Richards and Patrick Pease, Univ Northern Iowa, Cedar Falls, IA, United States
Spectral analysis of detrended ring-width data from a series of +400-year-old Douglas Firs on the SE flank of the Wind River Range indicates that tree growth from 1589-to-2013 shows a 2.5-to-4.5-year cyclicity (99%). This is within the limits of the generally accepted ~2-7 year ENSO cyclicity of the western Pacific. Our results also show a 16-year frequency (95%) suggesting possible additional influence from the Pacific Decadal Oscillation (PDO). Ring-widths here are most closely correlated to soil moisture conditions through the interaction(s) of abundant winter snowpack, summer rainfall, and average May-August temperatures during the 424-years from 1589-2013. Nearby climate records from the 1948-2013 period show that more favorable growth conditions exist here (higher snowpack+summer precipitation) during the El Niño cycle of ENSO. Our results fill a gap in knowledge of ENSO-like teleconnections during the Late Holocene that exists for the southern region of the Greater Yellowstone Ecosystem.