Drivers and Environmental Responses to the Changing Annual Snow Cycle of Northern Alaska

Abstract

Abstract Linkages between atmospheric, ecological, and biogeochemical variables in the changing Arctic are analyzed using long-term measurements near Utqiaġvik (formerly Barrow), Alaska. Two key variables are the date when snow disappears in spring, as determined primarily by atmospheric dynamics, precipitation, air temperature, winter snow accumulation, and cloud cover, and the date of onset of snowpack in autumn that is additionally influenced by ocean temperature and sea ice extent. In 2015 and 2016 the snow melted early at Utqiaġvik owing mainly to anomalous warmth during May of both years attributed to atmospheric circulation patterns, with 2016 having the record earliest snowmelt. These years are discussed in the context of a 115-yr snowmelt record at Utqiaġvik with a trend toward earlier melting since the mid-1970s (–2.86 days decade–1, 1975–2016). At nearby Cooper Island, where a colony of seabirds, black guillemots, have been monitored since 1975, timing of egg laying is correlated with Utqiaġvik snowmelt with 2015 and 2016 being the earliest years in the 42-yr record. Ice out at a nearby freshwater lagoon is also correlated with Utqiaġvik snowmelt. The date when snow begins to accumulate in autumn at Utqiaġvik shows a trend toward later dates (+4.6 days decade–1, 1975–2016), with 2016 being the latest on record. The relationships between the lengthening snow-free season and regional phenology, soil temperatures, fluxes of gases from the tundra, and to regional sea ice conditions are discussed. Better understanding of these interactions is needed to predict the annual snow cycles in the region at seasonal to decadal scales and to anticipate coupled environmental responses.