Seasonal characteristics and trends in precipitation partitioning in the Arctic

Abstract

Driven by growing impacts of changing precipitation amounts and phase on the Arctic's natural and built environment, we examine seasonal patterns and trends in Arctic precipitation and partitioning between its liquid and solid forms. Use is made of data from ERA5 reanalysis, Automated Surface Observing System stations over land, and a climatology based on present weather reports over the Arctic Ocean. In the Atlantic sector of the Arctic, most precipitation falls in liquid form in all seasons in its southern limits, but snowfall is high over its northern parts. Precipitation over the dry central Arctic Ocean and terrestrial polar deserts almost always falls as snow. Even during the summer, typically 50 % of precipitation over the central Arctic Ocean falls as snow. Over land, nearly all summer precipitation falls in liquid form, except in the Canadian Arctic Archipelago where summer snowfall is still common. Annual precipitation has increased since 1979, primarily in the Barents Sea sector, accompanied by generally downward trends in snowfall and, hence, upward trends in liquid precipitation. Across much of the Arctic, the liquid to total precipitation ratio has increased only in summer and autumn, while in the Atlantic sector, the liquid to total precipitation ratio has increased in fall and winter.