Framed within the Copernicus Climate Change Service (C3S) of the European Commission, the European Centre for Medium-Range Weather Forecasts (ECMWF) is producing an enhanced global dataset for the land component of the fifth generation of European ReAnalysis (ERA5), hereafter referred to as ERA5-Land. Once completed, the period covered will span from 1950 to the present, with continuous updates to support land monitoring applications. ERA5-Land describes the evolution of the water and energy cycles over land in a consistent manner over the production period, which, among others, could be used to analyse trends and anomalies. This is achieved through global high-resolution numerical integrations of the ECMWF land surface model driven by the downscaled meteorological forcing from the ERA5 climate reanalysis, including an elevation correction for the thermodynamic near-surface state. ERA5-Land shares with ERA5 most of the parameterizations that guarantees the use of the state-of-the-art land surface modelling applied to numerical weather prediction (NWP) models. A main advantage of ERA5-Land compared to ERA5 and the older ERA-Interim is the horizontal resolution, which is enhanced globally to 9 km compared to 31 km (ERA5) or 80 km (ERA-Interim), whereas the temporal resolution is hourly as in ERA5. Evaluation against independent in situ observations and global model or satellite-based reference datasets shows the added value of ERA5-Land in the description of the hydrological cycle, in particular with enhanced soil moisture and lake description, and an overall better agreement of river discharge estimations with available observations. However, ERA5-Land snow depth fields present a mixed performance when compared to those of ERA5, depending on geographical location and altitude. The description of the energy cycle shows comparable results with ERA5. Nevertheless, ERA5-Land reduces the global averaged root mean square error of the skin temperature, taking as reference MODIS data, mainly due to the contribution of coastal points where spatial resolution is important. Since January 2020, the ERA5-Land period available has extended from January 1981 to the near present, with a 2- to 3-month delay with respect to real time. The segment prior to 1981 is in production, aiming for a release of the whole dataset in summer/autumn 2021. The high spatial and temporal resolution of ERA5-Land, its extended period, and the consistency of the fields produced makes it a valuable dataset to support hydrological studies, to initialize NWP and climate models, and to support diverse applications dealing with water resource, land, and environmental management.The full ERA5-Land hourly (Muñoz-Sabater, 2019a) and monthly (Muñoz-Sabater, 2019b) averaged datasets presented in this paper are available through the C3S Climate Data Store at https://doi.org/10.24381/cds.e2161bac and https://doi.org/10.24381/cds.68d2bb30, respectively.

中文翻译：

---

ERA5-Land：用于土地应用的最先进的全球再分析数据集

在欧盟委员会哥白尼气候变化服务 (C3S) 的框架内，欧洲中期天气预报中心 (ECMWF) 正在为第五代欧洲再分析 (ERA5) 的陆地部分生成增强的全球数据集，以下简称作为ERA5-Land。完成后，涵盖的时期将从 1950 年到现在，持续更新以支持土地监测应用程序。ERA5-Land 描述了在生产期间以一致的方式在陆地上的水和能量循环的演变，除其他外，可用于分析趋势和异常。这是通过由 ERA5 气候再分析的缩小气象强迫驱动的 ECMWF 地表模型的全球高分辨率数值积分实现的，包括对热力学近地表状态的高程校正。ERA5-Land 与 ERA5 共享大多数参数化，这些参数化保证了应用于数值天气预报 (NWP) 模型的最先进地表建模的使用。ERA5-Land 与 ERA5 和较早的 ERA-Interim 相比的主要优势是水平分辨率，与 31 公里（ERA5）或 80 公里（ERA-Interim）相比，它在全球范围内增强到 9 公里，而时间分辨率是每小时如ERA5。对独立的原位观测和全球模型或基于卫星的参考数据集的评估显示了 ERA5-Land 在水文循环描述中的附加值，特别是增强了土壤水分和湖泊描述，以及河流流量估计的整体更好的一致性与可用的观察。然而，ERA5-陆地雪深场与 ERA5 相比表现出混合的性能，具体取决于地理位置和海拔高度。能量循环的描述显示了与 ERA5 相当的结果。尽管如此，ERA5-Land 降低了皮肤温度的全球平均均方根误差，作为参考 MODIS 数据，主要是由于沿海点的贡献，其中空间分辨率很重要。自 2020 年 1 月起，ERA5-Land 可用期限从 1981 年 1 月延长至近期，实时延迟了 2 至 3 个月。1981 年之前的片段正在制作中，目标是在 2021 年夏/秋发布整个数据集。本文中提供的完整 ERA5-Land 每小时（Muñoz-Sabater，2019a）和每月（Muñoz-Sabater，2019b）平均数据集可通过 C3S 气候数据存储获取，网址为https://doi.org/10.24381/cds.e2161bac和https://doi.org/10.24381/cds.68d2bb30分别。