Extratropical cyclones (ECs) play an important role in precipitation generation at mid-latitudes. EC circulation involves multiple precipitation-generating structures, raising questions regarding the origin of their moisture uptake. Our study aimed to identify the origin of precipitation using a Lagrangian approach by targeting EC characteristics in different regions. To achieve this goal, we focused on the 28 most intense ECs that affected the Iberian Peninsula (IP) in winter, with a detailed analysis of three cases, namely, Daniel, Elsa and Fabien, which occurred in December 2019. Our EC masking methodology defines target regions using the radius, warm conveyor belt (WCB) footprint stages, and a square root spiral contour centred on the cyclone, fitted to the decreasing mean sea level pressure field. Our results revealed that variations in the water budget radial target regions are driven by the intensity of moisture uptake over the spatial distribution. Furthermore, the moisture uptake patterns of the WCB ascent and outflow footprints closely resemble those of the central areas due to their geographical proximity. In the integral WCB uptake framework, the moisture gained from initial ascending particles within the inflow footprints effectively accounts for contributions from remote sources. Despite the broader precipitation inclusion, the spiral shape maintains systematic and efficient cyclone moisture dynamics.

中文翻译：

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温带气旋降水水源分析目标区评估：基于案例的分析


温带气旋（EC）在中纬度地区降水产生中发挥着重要作用。 EC 循环涉及多个降水生成结构，引发了有关其水分吸收来源的问题。我们的研究旨在通过针对不同地区的 EC 特征，使用拉格朗日方法来确定降水的来源。为了实现这一目标，我们重点关注了冬季影响伊比利亚半岛（IP）的28个最强烈的EC，并对2019年12月发生的三个案例进行了详细分析，即Daniel、Elsa和Fabien。我们的EC掩蔽方法使用半径、暖传送带 (WCB) 足迹阶段和以气旋为中心的平方根螺旋轮廓来定义目标区域，并适应递减的平均海平面压力场。我们的结果表明，水预算径向目标区域的变化是由空间分布上的水分吸收强度驱动的。此外，由于地理位置接近，WCB 上升和流出足迹的水分吸收模式与中心区域非常相似。在整体 WCB 吸收框架中，从流入足迹内初始上升颗粒获得的水分有效地解释了远程来源的贡献。尽管降水包含范围更广，但螺旋形状仍保持系统且高效的旋风水分动态。