Northern Chile is a region characterised by an extremely dry climate; however, there is a brief rainy season from December to March (austral summer), mainly above 3000 m a.s.l. It is interesting to consider where the humid air masses that generate such rain come from. For this purpose, daily precipitation data from 161 meteorological stations located in this area (18° S–19° S) were considered, and four clusters formed by k-means clustering. For each cluster, days of extreme precipitation (above 90th percentile) were selected to obtain flow strength (F), direction (D), and vorticity (Z) for each event according to the Jenkinson and Collison (JC) method. The back trajectory, for the previous 72 h, of air masses affecting the centroid of each cluster was determined by means of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The analyses were carried out at sea level (1013 hPa) and in the middle (500 hPa) and upper (250 hPa) troposphere. Surface circulation was not a determining factor in the occurrence of extreme events, but it did influence circulation at 500 and 250 hPa. For stations located in the northern Altiplano, moisture advection from the Amazon basin is evident due to the configuration of the Bolivian high—an upper level anticyclone that develops over the Bolivian Altiplano during austral summer. For stations located in the southern part of the study area, the main source of moisture is the Pacific Ocean, and the weather is related to the arrival of frontal systems and to the configuration of cut-off low pressure systems in the mid-troposphere.

智利北部是气候极为干燥的地区。然而，从12月至3月（夏季），雨季短暂，主要在海拔3000 m以上。考虑产生这种雨的湿空气来自何处是很有趣的。为此，考虑了来自该地区（18°S–19°S）的161个气象站的每日降水数据，并通过k均值聚类形成了四个聚类。对于每个群集，根据詹金森和科里森（JC）方法，选择几天的极端降水天数（高于90％）以获取每个事件的流动强度（F），方向（D）和涡度（Z）。过去72小时的后退轨迹 通过混合单粒子拉格朗日综合轨迹（HYSPLIT）模型确定影响每个星团质心的空气质量。在海平面（1013 hPa）和中层（500 hPa）和上层（250 hPa）对流层中进行了分析。表面循环不是决定极端事件发生的因素，但确实会影响500和250 hPa的循环。对于位于高原北部的台站，由于玻利维亚高地的构造而形成了明显的亚马逊流域对流。玻利维亚高地是南极夏季期间在玻利维亚高原上空发展的高层反气旋。对于位于研究区域南部的气象站，主要的水分来源是太平洋，