Variability in the climate of the Pacific Ocean and North America as expressed in the Mount Logan ice core

Abstract

In this paper, we explore the climate signal contained in the annual snow-accumulation time series from a high-altitude ice core drilled on Mount Logan in the Saint Elias mountain range of western Canada. With the global meteorological fields from the U.S. National Centers for Environmental Prediction re-analysis, we construct composites of the atmospheric circulation and temperature patterns associated with anomalous snow accumulation at the Mount Logan site over the period 1948-87. These results confirm, with an independent method, previous work that identified the existence of a coherent upper-tropospheric circulation anomaly extending over much of the North Pacific Ocean and North America that is associated with snow accumulation at the site. This anomaly has a similar structure to that associated with the extratropical response to the El Niño-Southern Oscillation. Coherent structures consistent with this circulation pattern also exist in both air- and land-temperature fields. In particular, heavy (light) snow accumulation at the site is associated with warmer (colder) air and surface temperatures over the North Pacific Ocean and North America. Over the North Pacific, the sea-surface temperature anomaly associated with heavy snow accumulation at the site has a "horseshoe" pattern that is similar to that associated with the Pacific Decadal Oscillation.