8 - Climate Regimes of the Arctic

Summary

Overview

The Arctic is home to a wide variety of climate conditions. This spectrum reflects, among other things, regional characteristics of the atmospheric circulation, elevation, distance from moisture sources (continentality), and properties of the surface. The present chapter both summarizes and builds on what we have already learned through a focus on some of these different climatic regimes. Up to now, relatively little attention has been paid to the Greenland Ice Sheet. This region is hence given special emphasis.

The Greenland Ice Sheet represents an extensive high elevation surface for which the albedo remains high throughout the year. Although these features distinguish its climate from other regions of the Arctic, ice sheet climates are nevertheless quite varied. The interior is very cold and dry, with summer temperatures well below freezing. Annual precipitation over the central part of the ice sheet, isolated from moisture sources, is around 100–200 mm. By comparison, the southeast coast is relatively warm and very moist. This region is strongly influenced by the North Atlantic cyclone track. Locally, in favored areas of orographic uplift, precipitation may exceed 2,000 mm. Some particularly interesting aspects of the ice sheet are its pronounced katabatic wind regime, related to radiational cooling, the significant role of sublimation on the moisture budget, and Greenland tip jets, which arise from interactions between coastal topography and the synoptic-scale wind slow. In 2012, almost all of the ice sheet briefly experienced summer melt, and summer melt extent has shown a general increase over the past several decades. The annual mass balance of the ice sheet is now clearly negative, contributing to sea level rise.