The sea ice coverage in the summer Arctic Ocean from the Beaufort to Laptev Seas continues to decrease, and the largest waves in the western Arctic open waters are increasing year by year. By looking into the historical wave events in the ERA-Interim reanalysis data, we discovered that more than half of the extreme events are caused by cyclones that are originating in the Arctic Ocean as well as in the mid-latitudes. During September, when the ice-free water area becomes largest each year, the percentage of extreme events caused by cyclones has increased from around 50% to almost 80% in the last four decades. Moreover, the locations of these extreme events are spreading from the Chukchi Sea to the east and west along the coasts and towards the central Arctic Ocean as depicted in the characteristic changes of the probability of sea states over the past decades. These findings are pertinent for safe navigation along the Northern Sea Route.

从博福特到拉普捷夫海，夏季北冰洋的海冰覆盖面积持续减少，北极西部开阔水域的最大海浪逐年增加。通过查看ERA-Interim重新分析数据中的历史波浪事件，我们发现超过一半的极端事件是由北冰洋以及中纬度地区的旋风造成的。在9月，每年无冰水域面积最大时，在过去的40年中，由旋风引起的极端事件所占的百分比已从大约50％增加到几乎80％。而且，这些极端事件的发生地点从楚科奇海沿沿海地区向东西方扩展，并向北冰洋中部扩散，如过去几十年海洋状况发生概率的特征性变化所描绘的那样。这些发现与沿北海航线的安全航行有关。