A comment about the seasonal cycle of snow

The winter fields indicate greater snow depths over the North American side of the Arctic Ocean. This is because temperatures are lower in this region, so that snow falling during the autumn months tends to more readily accumulate compared to other areas. However, March shows a tendency for deeper snow cover towards the Atlantic side of the Arctic Ocean. This is because winter snowfall is comparatively high in this area due to the northward penetration of storms associated with the Icelandic Low. Moving through spring and summer, the pattern of greater snow depths on the North American side is reestablished. Again, this is because this region tends to be colder, but here the effect is to result in slower melt. Most of the snow is melted by August. The season's first snowfall tends to occur in September. Because snow densities are broadly similar across the Arctic Ocean, the seasonal cycle of snow water equivalent is similar to that of snow depth.

Land areas with high winter snow depths correspond in part to regions with fairly high elevations (for example, Alaska and parts of Siberia). This is understood in that higher-elevation areas tend to be somewhat cooler, so snow can more easily accumulate in autumn. Snowfall may also be enhanced by orographic uplift of air masses. For other areas, such as Northwestern Eurasia, large snow depths appear to be more directly a reflection of synoptic activity. Note the low winter snow depths over east-central Siberia, where the strong Siberian High suppresses precipitation. The seasonal melt of the snow cover occurs earlier over the North American side. By July, snow cover has essentially disappeared.