Insolation-weighted assessment of Northern Hemisphere snow-cover and sea-ice variability

Abstract

The effects of sea-ice and snow-cover trends on the surface energy budget are assessed by scaling with the direct solar insolation. We have found that, consistent with other studies, an early spring melt has occurred in recent years in the unweighted data, but this trend is muted when the data are weighted by solar insolation. The onset of sea-ice growth and snow in the Fall, however, has no significant trend during the period of record. The effect of sea ice on the reflection of sunlight is largest in May and June when significant sea-ice coverage remains and the sun angle is high. Snow cover, in contrast, has its largest effect on the reflection of sunlight in April.