Patterns and sources of multidecadal oscillations in drought‐sensitive tree‐ring records from the central and southern Rocky Mountains

Abstract

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 (∼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.

Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States

“…2 B and E). Previous research has shown that, during positive AMO conditions, the central U.S. receives below-average precipitation, particularly during summer (1,8). The large positive correlations between smoothed AMO and drought frequency for the central U.S. (Fig.…”

“…Such long-term forecasts could help water managers plan for persistent drought across the conterminous United States (1). The urgency for such planning became evident when much of the U.S. was gripped by drought in 1996 and again in 1999-2003, evoking images of the dry 1930s and 1950s.…”

Associations of multi-decadal sea-surface temperature variability with US drought

“…Recently, research efforts have pointed to the Atlantic Ocean as a source of information to explain significant amounts of the D2M variability in North American, and possibly, global climate (Enfield et al, 2001;Gray et al, 2003Gray et al, , 2004Hodson, 2003, 2005;McCabe and Palecki, 2006). For example, the AMO has a strong relation to summer rainfall over the conterminous US, and may modulate the strength of the teleconnection between ENSO and winter precipitation (Enfield et al, 2001).…”

Multidecadal climate variability of global lands and oceans

“…More recently, research efforts have pointed to the Atlantic Ocean as a source of information to explain significant amounts of the variability in North American, and possibly, global climate (Enfield et al, 2001;Gray et al, 2003;Sutton and Hodson, 2003;Sutton and Hodson, 2005). For example, the AMO has a strong relation to summer rainfall over the conterminous United States, and may modulate the strength of the teleconnection between ENSO and winter precipitation (Enfield et al, 2001).…”