Editorial: Special collection – "Impact of polar observations on predictive skill".

Satellite sea-ice thickness observations are shown to be key to improving seasonal predictions of summer Arctic sea-ice concentration. The decrease in high-latitude surface albedo caused by the vanishing Arctic sea ice has a distinct signature on the Earth's radiative balance (Pistone I et al i ., [6]). The study shows that I in situ i observations play a critical role in initializing numerical weather forecasts during the winter season, while satellite microwave sounders are crucial during the summer season. [Extracted from the article]