ERA-Interim（再分析-臨時）
ERA-Interim（再分析-臨時）
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是氣候再分析數據集，涵蓋了1979年至2019年8月31日。ERA代表== “ ECMWF Re-Analysis”，是指ECMWF的一系列研究項目，產生了各種數據集（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-過渡生產於2019年8月31日停止
暫時直至另行通知，ERA-Interim（1979年1月1日至2019年8月31日）將繼續通過ECMWF Web API進行訪問。請記住，ERA-Interim的發布與數據集的參考日期相距大約三個月，因此ERA-Interim 2019年8月的數據將在2019年10月底提供。
現在可以從氣候數據存儲（CDS）中獲得ERA5（從ERA-Interim到ERA5的變化是什么？），強烈建議用戶遷移到ERA5（如何從ECMWF Web API遷移到CDS API）。
ERA-Interim是氣候再分析數據集，涵蓋了1979年至2019年8月31日。ERA代表“ ECMWF Re-Analysis”，是指ECMWF的一系列研究項目，產生了各種數據集（ERA-Interim，ERA-40 ，等等）。
ERA-Interim數據是開放訪問的，可以從ECMWF數據存檔免費下載以供所有使用。請參閱有關如何從ECMWF數據檔案下載ERA-Interim數據的指南。
ERA-Interim使用數字天氣預報（NWP）系統（IFS-CY31r2）的固定版本來生成重新分析的數據。固定版本可確保不斷發展的NWP系統不會導致虛假趨勢，盡管不斷變化的觀測系統可以創建此類趨勢。NWP系統將觀察值與先前的預測混合或同化，以獲得兩者的最佳擬合。這種混合的結果稱為分析，是下一次預測的起點。以這種方式，在越來越晚的時間產生數據。
ERA-Interim數據集包含大氣和地面參數：
模型級別，壓力級別，潛在溫度和潛在渦度的6小時大氣場
3小時表面場和每日垂直積分
日均收入的月平均值
天氣每月平均值為00 UTC，06 UTC，12 UTC，18 UTC
ERA-Interim數據以GRIB文件格式歸檔。
有關完整的詳細信息（包括參數列表），請參見ERA-Interim文檔。
有關更多詳細信息，請參見：
Berrisford，P.，P.Kållberg，S. Kobayashi，D. Dee，S.Uppala，AJ Simmons，P.Poli和H.Sato，2011年：ERA中期的大氣保護特性。QJR隕石。Soc。，137：1381–1399。doi： 10.1002 / qj.864
———————————————————————————————————
2、What are the changes from ERA-Interim to ERA5?（從ERA臨時版本到ERA5有什么變化？）
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.
本文檔介紹了ECMWF-ERA臨時存檔。ERA-Interim是對全球大氣的重新分析，涵蓋了自1979年以來的數據豐富時期（本來是ERA-Interim從1989年開始運行，但1979-1988年的10年延期是在2011年產生的），並實時持續進行。隨着ERA-Interim的及時發布，存檔的更新將每月進行。
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是一項自1979年以來的全球大氣再分析，並將繼續向前擴展至2019年8月31日。
用於生成ERA-Interim的數據同化系統基於IFS（Cy31r2）的2006版本。該系統包括帶有12小時分析窗口的4維變化分析（4D-Var）。數據集的空間分辨率在從地面到0.1 hPa的60個垂直水平上約為80 km（T255光譜）。
有關ERA-臨時存檔的詳細文檔，請參見Berrisford等。（2011）。在FAQ中可以找到有關此和其他ECMWF數據集的常見問題的答案。
ERA-Interim產品通常每月更新一次，且延遲兩個月（請參閱為什么我不能下載最近幾個月的ERA-Interim數據），以確保質量並糾正生產中的技術問題（如果有）。
可以從《皇家氣象學會季刊》 獲得描述ERA臨時重新分析的開放獲取 期刊文章。在IFS文檔Cy31r1中可以找到用於生成ERA-Interim的建模和數據同化系統的其他詳細信息 。我們知道ERA-Interim數據存在一些質量問題。
——————————————————————————————————