The Brooks Range is a moisture-sparse arctic/alpine environment with most of its small glaciers flowing to the north. Since many glaciers in the North American Arctic are fairly small and the distance between weather stations is great, it is probable that the action of undetected high-magnitude events has exerted a larger impact than previously supposed. McCall Glacier in the Brooks Range of Alaska is one of ten or so North American glaciers with a climate record that extends before 1966. To this day, McCall is the only glacier with a long-term climate record in the Alaskan Arctic. The closest weather station to McCall Glacier – Barter Island, 100km distance – has been in operation since 1947. This continuous record, in conjunction with the nearly decadal visits to McCall glacier starting in 1957, creates a climate record unlike any other in North America. The proximity of Barter Island enables examination of high-magnitude weather events in the context of long-term climate change. The most recent studies on McCall Glacier have included meteorological data that can be compared to the IGY, IHD, and 1990’s meteorological data, as well as Barter Island’s continuous record. These data can be evaluated to determine the mass-balance changes of the glacier over time, as well as determine the feasibility of predicting future mass-balance change. (Figure 1)

The small glaciers of the eastern Brooks Range in Northeast Alaska are examples of marginal zone glaciers. Their location in a generally data sparse area makes them logical candidates for extraction of climate change proxy records. However, their small size makes it important that the occurrence and influence of high magnitude weather events be fully encompassed. This will facilitate proper framing of conclusions drawn from small glacier activity for climate change studies.

High magnitude weather events, defined as those of potential impact to McCall Glacier mass balance, which includes those bringing snow, rain, high winds, or strong temperature advection episodes, are identified and placed into their broader synoptic context. Specifically, data records were used first to identify occurrences of these events. Then large scale atmospheric flow patterns were obtained using reanalysis data from the National Centers for Environmental Prediction (NCEP, formerly "NMC") and the National Center for Atmospheric Research (NCAR) online plotting facility. Data for this work came from several sources, including data rescued from three IGY stations in the local vicinity (McCall Glacier, Lake Peters, and Chamberlin Glacier) (Orvig 1961, Hobbie 2007, and Larsson 1960), data from nearby weather stations, and data from more recent surveys on McCall Glacier (Wendler et al 1972, Rabus 1998, and Nolan 2006)

Results indicate McCall glacier is subject to periodic scour by high-wind events. Heavy snow fall events frequently do not lead to large accumulation because they are often accompanied by high winds which remove much of the snow from the central part of the glacier. Synoptic-scale flow regimes that accompany these events varied but high magnitude wind events were typically accompanied by winds from the northeast with a center of high pressure positioned in the middle of the state. (Figure 2) Snowfall without wind is often associated with a strong pressure gradient running diagonally across the state bringing moisture across the interior from the Bering Sea. The general synoptic situation of the state is a low pressure system sitting to the north, dipping to varying degrees into the interior.

Overall, mass loss on McCall Glacier due to non-melting ablation events (snow deflation) tend to be driven by synoptic conditions in which a system brings larger-scale winds from the northeast. By comparison to many glaciers that are studied in detail around the world, McCall Glacier has very small precipitation and ablation measurements, and changes very little from one year to the next, making the long term study of this glacier of more vital importance than more widely fluctuating glaciers.