This article analyzes recent trends in extreme precipitation in the Southwestern Alps and compares these trends to changes in the occurrence of the atmospheric influences generating extremes. We consider a high-resolution precipitation dataset of 1 × 1 km${}^2$ for the period 1958–2017. A robust method of trend estimation in extreme precipitation is considered, based on nonstationary extreme value distribution and a homogeneous neighborhood approach. The results show contrasting trends in extreme precipitation depending on the season. In autumn, most of Southern France shows significant increasing trends, with increase in the 20-year return level between 1958 and 2017 as large as its average value over the period, while the Northern French Alps and the Swiss Valais show decreasing extremes. In winter, significant increasing extremes are found in the valleys and medium mountain areas surrounding the Northern French Alps, while the inner French Alps, the Swiss Valais and the Aosta Valley show significant decreasing trends. In the other seasons, the significant trends are mostly negative in the Mediterranean area. Comparing these trends to changes in the occurrence of the atmospheric influences generating extremes shows that part of the significant changes in extremes can be explained by changes in the dominant influences, in particular in the Mediterranean influenced region that shows the most organized trends. In particular, the strong positive trends in extreme precipitation in autumn in Southern France are concomitant with an increase in Mediterranean influence generating extremes.

本文分析了西南阿尔卑斯山极端降水的近期趋势，并将这些趋势与产生极端事件的大气影响发生的变化进行了比较。我们考虑一个 1 × 1 公里的高分辨率降水数据集${}^2$1958-2017 年期间。考虑了一种基于非平稳极值分布和齐次邻域方法的极端降水趋势估计的稳健方法。结果显示了不同季节极端降水的对比趋势。秋季，法国南部大部分地区呈现显着上升趋势，1958年至2017年的20年收益率上升幅度达到其同期平均值，而法国北部阿尔卑斯山和瑞士瓦莱州则呈下降趋势。在冬季，在法国北部阿尔卑斯山周围的山谷和中山地区发现了显着增加的极端事件，而法国内阿尔卑斯山、瑞士瓦莱州和奥斯塔山谷则呈现出显着减少的趋势。在其他季节，地中海地区的显着趋势大多是负面的。将这些趋势与产生极端事件的大气影响发生的变化进行比较表明，极端事件的部分显着变化可以用主要影响的变化来解释，特别是在显示出最有组织的趋势的地中海地区。特别是，法国南部秋季极端降水的强烈积极趋势伴随着地中海影响的增加而产生的极端事件。特别是在受地中海影响的地区，表现出最有组织的趋势。特别是，法国南部秋季极端降水的强烈积极趋势伴随着地中海影响的增加而产生的极端事件。特别是在受地中海影响的地区，表现出最有组织的趋势。特别是，法国南部秋季极端降水的强烈积极趋势伴随着地中海影响的增加而产生的极端事件。