A Comparison of Three Millennial-Length Streamflow Reconstructions from Tree Rings Along a North-South Gradient Straddling the ENSO Dipole Transition Zone

Abstract:

Northern Utah includes one of the largest and fastest growing metropolitan areas in the semi-arid Intermountain West. Yet, this region faces considerable uncertainty regarding water resource availability due to its location in the transition zone of the north-south precipitation dipole associated with ENSO. Previous research has demonstrated that this transition zone migrates latitudinally, such that hydroclimatic conditions in northern vs. central Utah may be alternately in- or out-of-phase. We present a synthesis of three independent, millennial-length tree-ring based streamflow reconstructions from watersheds spanning 4 degrees of latitude, developed from a network of Utah juniper and low-elevation bristlecone pine chronologies. The reconstructions demonstrate periods of considerable synchrony and asynchrony, shedding light on the spatially and temporally variable role of teleconnections as drivers of hydroclimate. We also discuss the implications of these findings for our water manager partners throughout northern Utah, and demonstrate the benefit of millennial-length reconstructions in improving established hydroclimate forecast models in the face of climatic change.