Warm Airmass Intrusions (WAIs) from the mid-latitudes significantly impact the Arctic water budget. Here, we combine water vapor isotope measurements from the MOSAiC expedition, with a Lagrangian-based process attribution diagnostic to track moisture transformation in the central Arctic Ocean during two WAIs, under contrasting sea-ice concentrations (SIC). During winter with high SIC, two moisture supplies are identified. The first is Arctic moisture, locally-sourced over the sea ice, with isotopic composition influenced by kinetic fractionation during ice-cloud formation and vapor deposition. This moisture is rapidly overprinted by low-latitude moisture advected poleward during WAI. In summer under low SIC, moisture is supplied through evaporation from land and ocean, with moisture removal via liquid-cloud and dew formation. The isotopic composition reflects the influence of higher relative humidity at the evaporation sites. Given the projected increase of frequency and duration of WAIs, our study contributes to assessing process changes in the Arctic water cycle.

中文翻译：

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暖空气侵入北极中的水分转化：稳定水同位素的过程归因


来自中纬度地区的暖气团入侵 （WAI） 对北极的水资源收支产生了重大影响。在这里，我们将 MOSAiC 探险队的水蒸气同位素测量与基于拉格朗日的过程归因诊断相结合，以跟踪在对比海冰浓度 （SIC） 下两次 WAI 期间北冰洋中部的水分变化。在 SIC 高的冬季，确定了两个水分供应。首先是北极水汽，当地来源于海冰上，同位素组成受冰云形成和气相沉积过程中动力学分馏的影响。在 WAI 期间，这种水分被向极地平流的低纬度水分迅速叠印。在低 SIC 的夏季，水分通过陆地和海洋的蒸发提供，通过液云和露水的形成去除水分。同位素组成反映了蒸发地点较高相对湿度的影响。鉴于 WAI 的频率和持续时间预计会增加，我们的研究有助于评估北极水循环的过程变化。