A comment about the seasonal cycle of temperature

The mean seasonal cycle of temperature is simply described. During winter, temperatures decrease sharply from the northern North Atlantic to the central Arctic Ocean. The high temperatures over the Atlantic sector arise from the moderating influence of ice-free waters in this region, coupled with the frequent cyclone activity associated with the Icelandic Low transporting warm air polewards. Similarly, high temperatures are found south of Alaska associated with the Aleutian Low. The lowest winter temperatures occur over Siberia in association with the cold Siberian High. Standard deviations are also high over Siberia due to variations in the strength of the Siberian High from year to year. The low temperatures over Greenland reflect the high elevation of the ice sheet. While temperatures are of course higher everywhere in summer, the spatial variability seen in winter is much less pronounced in summer, and standard deviations are lower. Temperatures are highest over land areas in summer because the surface is snow free and can be easily heated by the strong solar radiation flux. Over the Arctic Ocean, temperatures are close to zero. This occurs because the sea ice cover is at its melting point, which keeps air temperatures near freezing. The autumn months illustrate the transition back to the winter pattern, with higher temperatures over the Atlantic and south of Alaska, and low temperatures over Siberia and the Greenland ice sheet.