The ERA5 global reanalysis
The ERA5 global reanalysis
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DOI：
10.1002/qj.3803
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发表时间：
2020-06-15
影响因子：
8.9
通讯作者：
Thepaut, Jean-Noel
中科院分区：
文献类型：
--
作者：
Hersbach, Hans;Bell, Bill;Thepaut, Jean-Noel
在哥白尼气候变化服务（C3 S）内，ECMWF正在制作ERA 5再分析，一旦完成，将包含1950年以来全球大气，陆地表面和海浪的详细记录。这一新的再分析取代了2006年开始的ERA中期再分析（从1979年开始）。ERA 5基于2016年投入运行的综合预报系统（IFS）Cy 41 r2。因此，ERA 5受益于十年来在模型物理学、核心动力学和数据同化方面的发展。与ERA-Interim的80公里水平分辨率相比，ERA 5的水平分辨率显著提高，达到31公里，此外，ERA 5还具有全程每小时的输出，以及来自集合的不确定性估计（3小时，水平分辨率的一半）。本文介绍了ERA 5的一般设置，以及对特征和性能的基本评价，重点是目前公开的1979年以来的数据集。根据ERA 5分析的重新预测显示，与ERA-Interim相比，技能增加了一天。在同化之前与无线电探空仪和PILOT数据的比较表明，对流层的温度、风和湿度的拟合得到了改善，但平流层的拟合没有改善。与独立浮标数据的比较表明，海洋波高的拟合得到了很大的改善。不确定性估计反映了ERA 5中使用的观测系统的演变。增强的时间和空间分辨率允许详细的天气系统的演变。对于降水量，全球平均与月平均GPCP数据的相关性从67%增加到77%。在一般情况下，低频变率被认为是很好的代表性，从10百帕向下的一般模式的异常温度匹配的ERA-临时，MERRA-2和JRA-55再分析。
Within the Copernicus Climate Change Service (C3S), ECMWF is producing the ERA5 reanalysis which, once completed, will embody a detailed record of the global atmosphere, land surface and ocean waves from 1950 onwards. This new reanalysis replaces the ERA-Interim reanalysis (spanning 1979 onwards) which was started in 2006. ERA5 is based on the Integrated Forecasting System (IFS) Cy41r2 which was operational in 2016. ERA5 thus benefits from a decade of developments in model physics, core dynamics and data assimilation. In addition to a significantly enhanced horizontal resolution of 31 km, compared to 80 km for ERA-Interim, ERA5 has hourly output throughout, and an uncertainty estimate from an ensemble (3-hourly at half the horizontal resolution). This paper describes the general set-up of ERA5, as well as a basic evaluation of characteristics and performance, with a focus on the dataset from 1979 onwards which is currently publicly available. Re-forecasts from ERA5 analyses show a gain of up to one day in skill with respect to ERA-Interim. Comparison with radiosonde and PILOT data prior to assimilation shows an improved fit for temperature, wind and humidity in the troposphere, but not the stratosphere. A comparison with independent buoy data shows a much improved fit for ocean wave height. The uncertainty estimate reflects the evolution of the observing systems used in ERA5. The enhanced temporal and spatial resolution allows for a detailed evolution of weather systems. For precipitation, global-mean correlation with monthly-mean GPCP data is increased from 67% to 77%. In general, low-frequency variability is found to be well represented and from 10 hPa downwards general patterns of anomalies in temperature match those from the ERA-Interim, MERRA-2 and JRA-55 reanalyses.