标题： 揭示极地涡旋的边缘 显示英文标题

标题： Uncovering the Edge of the Polar Vortex

摘要： 极涡在臭氧洞的形成中起着关键作用，并可能导致严重的天气异常。 它们的边界，称为涡旋“边缘”，通常通过依赖于参考系的方法或返回非物质结构的方法来识别，因此不适合评估物质输运屏障。 利用北半球等熵面上的二维速度数据，我们表明椭圆拉格朗日相干结构（LCSs）能够正确识别将相干涡旋核心与周围非相干表面区域分开的最外层物质表面。 尽管LCSs是纯运动学构造，但我们发现在所识别的涡旋边界处温度和臭氧浓度存在显著差异。 我们还表明，基于位涡的方法尽管简单，却错误地识别了涡旋边缘的正确范围。 最后，利用涡旋在不同等熵层上的收缩情况，我们观察到涡旋内部垂直运动幅度存在与先前结果一致的趋势。 显示英文摘要

摘要： The polar vortices play a crucial role in the formation of the ozone hole and can cause severe weather anomalies. Their boundaries, known as the vortex `edges', are typically identified via methods that are either frame-dependent or return non-material structures, and hence are unsuitable for assessing material transport barriers. Using two-dimensional velocity data on isentropic surfaces in the northern hemisphere, we show that elliptic Lagrangian Coherent Structures (LCSs) identify the correct outermost material surface dividing the coherent vortex core from the surrounding incoherent surf zone. Despite the purely kinematic construction of LCSs, we find a remarkable contrast in temperature and ozone concentration across the identified vortex boundary. We also show that potential vorticity-based methods, despite their simplicity, misidentify the correct extent of the vortex edge. Finally, exploiting the shrinkage of the vortex at various isentropic levels, we observe a trend in the magnitude of vertical motion inside the vortex which is consistent with previous results.