Abstract. This work introduces the S2M (SAFRAN - SURFEX/ISBA-Crocus - MEPRA) meteorological and snow cover reanalysis in the French Alps, Pyrenees and Corsica, spanning the time period from 1958 to 2020. The simulations are made over elementary areas, referred to as massifs, designed to represent the main drivers of the spatial variability observed in mountain ranges (elevation, slope and aspect). The meteorological reanalysis is performed by the SAFRAN system, which combines information from numerical weather prediction models (ERA-40 reanalysis from 1958 to 2002, ARPEGE from 2002 to 2020) and the best possible set of available in-situ meteorological observations. SAFRAN outputs are used to drive the Crocus detailed snow cover model, which is part of the land surface scheme SURFEX/ISBA. This model chain provides simulations of the evolution of the snow cover, underlying ground, and the associated avalanche hazard using the MEPRA model. This contribution describes and discusses the main climatological characteristics (climatology, variability and trends), and the main limitations of this dataset. We provide a short overview of the scientific applications using this reanalysis in various scientific fields related to meteorological conditions and the snow cover in mountain areas. An evaluation of the skill of S2M is also displayed, in particular through comparison to 665 independent in-situ snow depth observations. Further, we describe the technical handling of this open access data set, available at this address: http://dx.doi.org/10.25326/37#v2020.2. Scientific publications using this dataset must mention in the acknowledgments: "The S2M data are provided by Météo-France - CNRS, CNRM Centre d’Etudes de la Neige, through AERIS" and refer to it as Vernay et al. (2020).

中文翻译：

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法国山区的 S2M 气象和积雪再分析、描述和评估（1958-2020）

摘要。这项工作介绍了 1958 年至 2020 年期间法国阿尔卑斯山、比利牛斯山脉和科西嘉岛的 S2M（SAFRAN - SURFEX/ISBA-Crocus - MEPRA）气象和积雪再分析。模拟是在基本区域进行的，称为地块，旨在代表在山脉（海拔、坡度和坡向）中观察到的空间变化的主要驱动因素。气象再分析由 SAFRAN 系统执行，该系统结合了数值天气预报模型（1958 年至 2002 年的 ERA-40 再分析，2002 年至 2020 年的 ARPEGE）和可用的最佳现场气象观测资料。SAFRAN 输出用于驱动 Crocus 详细积雪模型，该模型是地表方案 SURFEX/ISBA 的一部分。该模型链提供了使用 MEPRA 模型对积雪、下伏地面和相关雪崩危害演变的模拟。本贡献描述并讨论了主要气候特征（气候学、变异性和趋势）以及该数据集的主要局限性。我们简要概述了在与气象条件和山区积雪有关的各个科学领域中使用这种再分析的科学应用。还显示了对 S2M 技能的评估，特别是通过与 665 个独立的现场雪深观测进行比较。此外，我们描述了这个开放获取数据集的技术处理，可从以下地址获得：http://dx.doi.org/10.25326/37#v2020.2。使用此数据集的科学出版物必须在致谢中提及：“S2M 数据由法国气象局 - CNRS、CNRM 中心 d'Etudes de la Neige，通过 AERIS 提供”，并将其称为 Vernay 等人。(2020)。