The Arctic is experiencing amplified climate warming, decreasing sea ice extent, increasingly earlier springtime snowmelt, and a related increase in fire activity. The transition from cold to warm season in the Arctic strongly varies between years, but our understanding of temperature and surface energy budget changes over the springtime is limited. Here we investigate intraseasonal variability of Arctic springtime temperature and surface energy budget components and their interannual trends over 40 years (1981–2020) across the terrestrial Arctic (above 60° N) using ERA5-Land reanalysis data. We found the central and western Siberian regions to have the highest interannual variability in spring temperature anomaly among all Arctic regions during the 40-year period. Also in this region, we discovered the strength increased for heat extremes and decreased for cold extremes when comparing the first and the last 20 years of our study. Peaks in composited extreme temperature and surface energy budget anomalies were observed to occur concurrently, indicating temperature extremes are not driven by surface energy budget components. Lastly, by utilizing power spectrum analyses, we identified the primary driver of temperature anomaly interannual variability to be operating at a 1- to 2-week frequency. Based on our findings and observations in the recent literature, we hypothesize that the observed interannual variability in springtime temperature can be attributed to increased Arctic sea ice decline and an increase in the frequency and strength of associated atmospheric blocking events.

中文翻译：

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北极春季温度和能量通量的年际变化是由 1 至 2 周频率的大气事件驱动的

北极正在经历气候变暖加剧、海冰范围缩小、春季融雪日益提前以及火灾活动相应增加。北极从冷季到暖季的转变因年份而异，但我们对春季温度和地表能量收支变化的了解有限。在这里，我们使用 ERA5-Land 再分析数据研究了北极春季温度和地表能量预算成分的季节内变化及其 40 年来（1981-2020）整个北极陆地（北纬 60° 以上）的年际趋势。我们发现，40年来，西伯利亚中部和西部地区的春季气温异常年际变化是所有北极地区中最高的。同样在这个地区，在比较我们研究的前 20 年和最后 20 年时，我们发现极端炎热时强度增加，极端寒冷时强度下降。观察到复合极端温度和表面能量收支异常的峰值同时出现，表明极端温度不是由表面能量收支组成部分驱动的。最后，通过利用功率谱分析，我们确定了温度异常年际变化的主要驱动因素以 1 至 2 周的频率运行。根据我们在最近文献中的发现和观察，我们假设观察到的春季温度的年际变化可归因于北极海冰减少的增加以及相关大气阻塞事件的频率和强度的增加。