ECMWF数据集ERA-Interim介绍----大气数据研究
ERA-Interim（再分析-临时）
ERA-Interim（再分析-临时）
ERA-Interim is a climate reanalysis dataset, covering the period from 1979 to 31st August 2019. ERA stands for ‘ECMWF Re-Analysis’ and refers to a series of research projects at ECMWF which produced various datasets (ERA-Interim, ERA-40, etcetera).
ERA-Interim是气候再分析数据集，涵盖了1979年至2019年8月31日。ERA代表== “ ECMWF Re-Analysis”，是指ECMWF的一系列研究项目，产生了各种数据集（ERA-Interim，ERA-40 ，等等）。
———————————————————————————————————
1、What is ERA-Interim？
[https://confluence.ecmwf.int/display/CKB/What+is+ERA-Interim](https://confluence.ecmwf.int/display/CKB/What+is+ERA-Interim)
ERA-Interim production stopped on 31st August 2019
For the time being and until further notice, ERA-Interim (1st January 1979 to 31st August 2019) shall continue to be accessible through the ECMWF Web API. Keeping in mind that ERA-Interim is published with an offset of about three months from the dataset’s reference date, ERA-Interim August 2019 data will be made available towards the end of October 2019.
ERA5 is now available from the Climate Data Store (CDS) (What are the changes from ERA-Interim to ERA5?) and users are strongly advised to migrate to ERA5 (How to migrate from ECMWF Web API to CDS API).
ERA-Interim is a climate reanalysis dataset, covering the period from 1979 to 31st August 2019. ERA stands for ‘ECMWF Re-Analysis’ and refers to a series of research projects at ECMWF which produced various datasets (ERA-Interim, ERA-40, etcetera).
ERA-Interim data is open access and free to download for all uses from the ECMWF data archive. Please see our guidelines on How to download ERA-Interim data from the ECMWF data archive.
ERA-Interim uses a fixed version of a numerical weather prediction (NWP) system (IFS - CY31r2) to produce reanalysed data. The fixed version ensures that no spurious trends are caused by an evolving NWP system, though the changing observing system can create such trends. The NWP system blends, or assimilates observations with a previous forecast to obtain the best fit to both. The result of this blending is called an analysis and is the starting point for the next forecast. In this manner, data is produced at increasingly later times.
The ERA-Interim dataset contains atmospheric and surface parameters:
6-hourly atmospheric fields on model levels, pressure levels, potential temperature and potential vorticity
3-hourly surface fields and daily vertical integrals
Monthly averages of daily means
Synoptic monthly averages at 00 UTC, 06 UTC, 12 UTC, 18 UTC
ERA-Interim data is archived in the GRIB file format.
Please see ERA-Interim documentation for full details (including list of parameters).
For further details please see:
Berrisford, P., P. Kållberg, S. Kobayashi, D. Dee, S. Uppala, A. J. Simmons, P. Poli, and H. Sato, 2011: Atmospheric conservation properties in ERA-Interim. Q.J.R. Meteorol. Soc., 137: 1381–1399. doi: 10.1002/qj.864
ERA-过渡生产于2019年8月31日停止
暂时直至另行通知，ERA-Interim（1979年1月1日至2019年8月31日）将继续通过ECMWF Web API进行访问。请记住，ERA-Interim的发布与数据集的参考日期相距大约三个月，因此ERA-Interim 2019年8月的数据将在2019年10月底提供。
现在可以从气候数据存储（CDS）中获得ERA5（从ERA-Interim到ERA5的变化是什么？），强烈建议用户迁移到ERA5（如何从ECMWF Web API迁移到CDS API）。
ERA-Interim是气候再分析数据集，涵盖了1979年至2019年8月31日。ERA代表“ ECMWF Re-Analysis”，是指ECMWF的一系列研究项目，产生了各种数据集（ERA-Interim，ERA-40 ，等等）。
ERA-Interim数据是开放访问的，可以从ECMWF数据存档免费下载以供所有使用。请参阅有关如何从ECMWF数据档案下载ERA-Interim数据的指南。
ERA-Interim使用数字天气预报（NWP）系统（IFS-CY31r2）的固定版本来生成重新分析的数据。固定版本可确保不断发展的NWP系统不会导致虚假趋势，尽管不断变化的观测系统可以创建此类趋势。NWP系统将观察值与先前的预测混合或同化，以获得两者的最佳拟合。这种混合的结果称为分析，是下一次预测的起点。以这种方式，在越来越晚的时间产生数据。
ERA-Interim数据集包含大气和地面参数：
模型级别，压力级别，潜在温度和潜在涡度的6小时大气场
3小时表面场和每日垂直积分
日均收入的月平均值
天气每月平均值为00 UTC，06 UTC，12 UTC，18 UTC
ERA-Interim数据以GRIB文件格式归档。
有关完整的详细信息（包括参数列表），请参见ERA-Interim文档。
有关更多详细信息，请参见：
Berrisford，P.，P.Kållberg，S. Kobayashi，D. Dee，S.Uppala，AJ Simmons，P.Poli和H.Sato，2011年：ERA中期的大气保护特性。QJR陨石。Soc。，137：1381–1399。doi： 10.1002 / qj.864
———————————————————————————————————
2、What are the changes from ERA-Interim to ERA5?（从ERA临时版本到ERA5有什么变化？）
https://confluence.ecmwf.int/pages/viewpage.action?pageId=74764925
———————————————————————————————————
This document describes the ERA-Interim Archive at ECMWF. ERA-Interim is a reanalysis of the global atmosphere covering the data-rich period since 1979 (originally, ERA-Interim ran from 1989, but the 10 year extension for 1979-1988 was produced in 2011), and continuing in real time. As ERA-Interim continues forward in time, updates of the Archive will take place on a monthly basis.
ERA-Interim is a global atmospheric reanalysis from 1979 and will continue to be extended forward in time until 31 August 2019.
本文档介绍了ECMWF-ERA临时存档。ERA-Interim是对全球大气的重新分析，涵盖了自1979年以来的数据丰富时期（本来是ERA-Interim从1989年开始运行，但1979-1988年的10年延期是在2011年产生的），并实时持续进行。随着ERA-Interim的及时发布，存档的更新将每月进行。
The data assimilation system used to produce ERA-Interim is based on a 2006 release of the IFS (Cy31r2). The system includes a 4-dimensional variational analysis (4D-Var) with a 12-hour analysis window. The spatial resolution of the data set is approximately 80 km (T255 spectral) on 60 vertical levels from the surface up to 0.1 hPa.
For a detailed documentation of the ERA-Interim Archive see Berrisford et al. (2011). Answers to frequently asked questions about this and other ECMWF datasets can be found in the FAQ.
ERA-Interim products are normally updated once per month, with a delay of two months (see Why can’t I download ERA-Interim data for recent months) to allow for quality assurance and for correcting technical problems with the production, if any.
An open-access journal article describing the ERA-Interim reanalysis is available from the Quarterly Journal of the Royal Meteorological Society. Additional details of the modelling and data assimilation system used to produce ERA-Interim can be found in the IFS documentation Cy31r1. We are aware of several quality issues with ERA-Interim data.
ERA-Interim是一项自1979年以来的全球大气再分析，并将继续向前扩展至2019年8月31日。
用于生成ERA-Interim的数据同化系统基于IFS（Cy31r2）的2006版本。该系统包括带有12小时分析窗口的4维变化分析（4D-Var）。数据集的空间分辨率在从地面到0.1 hPa的60个垂直水平上约为80 km（T255光谱）。
有关ERA-临时存档的详细文档，请参见Berrisford等。（2011）。在FAQ中可以找到有关此和其他ECMWF数据集的常见问题的答案。
ERA-Interim产品通常每月更新一次，且延迟两个月（请参阅为什么我不能下载最近几个月的ERA-Interim数据），以确保质量并纠正生产中的技术问题（如果有）。
可以从《皇家气象学会季刊》 获得描述ERA临时重新分析的开放获取 期刊文章。在IFS文档Cy31r1中可以找到用于生成ERA-Interim的建模和数据同化系统的其他详细信息 。我们知道ERA-Interim数据存在一些质量问题。
——————————————————————————————————
