In this study, warm and moist air intrusions (WaMAIs) over the Arctic Ocean sectors of Barents Sea, Kara Sea, Laptev Sea, East Siberian Sea, Chukchi Sea, and Beaufort Sea in 40 recent winters (from 1979 to 2018) are identified from the ERA5 reanalysis using both Eulerian and Lagrangian views. The analysis shows that WaMAIs, fueled by Arctic blocking, cause a relative surface warming and hence a sea-ice reduction by exerting positive anomalies of net thermal irradiances and turbulent fluxes on the surface. Over Arctic Ocean sectors with land-locked sea ice in winter, such as Laptev Sea, East Siberian Sea, Chukchi Sea, and Beaufort Sea, the total surface energy-budget is dominated by net thermal irradiance. From a Lagrangian perspective, total water path (TWP) increases linearly with the downstream distance from the sea-ice edge over the completely ice-covered sectors, inducing almost linearly increasing net thermal irradiance and total surface energy-budget. However, over the Barents Sea, with an open ocean to the south, total net surface energy-budget is dominated by the surface turbulent flux. With the energy in the warm-and-moist air continuously transported to the surface, net surface turbulent flux gradually decreases with distance, especially within the first 2^∘ north of the ice edge, inducing a decreasing but still positive total surface energy-budget. The boundary-layer energy-budget patterns over the Barents Sea can be categorized into three classes: radiation-dominated, turbulence-dominated, and turbulence-dominated with cold dome, comprising about 52 %, 40 %, and 8 % of all WaMAIs, respectively. Statistically, turbulence-dominated cases with or without cold dome occur along with 1 order of magnitude larger large-scale subsidence than the radiation-dominated cases. For the turbulence-dominated category, larger turbulent fluxes are exerted to the surface, probably because of stronger wind shear. In radiation-dominated WaMAIs, stratocumulus develops more strongly and triggers intensive cloud-top radiative cooling and related buoyant mixing that extends from cloud top to the surface, inducing a thicker well-mixed layer under the cloud. With the existence of cold dome, fewer liquid water clouds were formed, and less or even negative turbulent fluxes could reach the surface.

中文翻译：

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温暖潮湿的空气侵入冬季北极：近地表能量收支的拉格朗日观点

在这项研究中，在最近的 40 个冬季（从 1979 年到 2018 年）中，确定了北冰洋巴伦支海、喀拉海、拉普捷夫海、东西伯利亚海、楚科奇海和博福特海区域的暖湿空气入侵 (WaMAIs)使用欧拉和拉格朗日观点的 ERA5 再分析。分析表明，由北极阻塞推动的 WaMAI 通过在表面施加净热辐照度和湍流通量的正异常，导致相对地表变暖，从而导致海冰减少。在冬季有内陆海冰的北冰洋区域，如拉普捷夫海、东西伯利亚海、楚科奇海和博福特海，总地表能量预算主要由净热辐照度决定。从拉格朗日角度来看，总水路径（TWP）随着从海冰边缘到完全冰覆盖区域的下游距离线性增加，导致净热辐照度和总表面能量预算几乎线性增加。然而，在巴伦支海，南面是一片开阔的海洋，总净地表能量预算主要由地表湍流通量决定。随着暖湿空气中的能量不断输送到地表，净地表湍流通量随着距离的增加而逐渐减小，尤其是在前2^∘冰边缘以北，导致总地表能量预算减少但仍为正。巴伦支海的边界层能量预算模式可分为三类：辐射主导、湍流主导和冷穹湍流主导，约占所有 WaMAIs 的 52%、40% 和 8%，分别。从统计数据来看，无论有无冷穹，湍流主导的情况下都会发生比辐射主导的情况大 1 个数量级的大规模沉降。对于以湍流为主的类别，较大的湍流通量施加到地表，可能是因为更强的风切变。在以辐射为主的 WaMAIs 中，层积云发展得更加强烈，并引发强烈的云顶辐射冷却和相关的从云顶延伸到地表的浮力混合，在云层下形成更厚的混合层。由于冷穹的存在，液态水云的形成减少了，到达地表的湍流也更少甚至为负。