Eclipse Ice Core Accumulation and Stable Isotope Variability as an Indicator of North Pacific Climate

Three ice cores retrieved from the Eclipse Icefield in Yukon Territory, Canada provide a unique, high- resolution record reflecting climatic and environmental conditions in the North Pacific and western-North American region. A stacked core record was produced to filter noise and extract the dominant weather and climate signals. Accumulation and stable isotopes records were studied and calibrated with modern instrumental data from 1948-2001 to determine their level of utility in reconstructing past precipitation, 500 hPa geopotential heights and surface temperature patterns. Results reveal that the most extreme years and seasons of precipitation are strongly influenced by the average amplitude and position of the Rossby wave in the eastern Pacific region and western-North America. High (low) accumulation is associated with a stronger (weaker) mean Aleutian low and stronger (weaker) mean western-North American ridge. The sign of the PNA correlated well during these extreme accumulation periods, as did the Multivariate ENSO Index to a slightly lesser degree. This result strongly supports extreme accumulation years as a proxy for North Pacific basin atmospheric circulation. Composites of 500 hPa geopotential height anomaly patterns during high and low years of stable isotope fractionation yield high interannual variability, thus calling into question the climatic reconstruction utility of stable isotopes from this drillsite.