ERA-15 Project

ECMWF has provided global atmospheric analyses from its archive for many years. The ERA-15 project was devised in response to wishes expressed by many users for a data set generated by a modern, consistent, and invariant data assimilation system.

The project began in February 1993, and a re-analysis for the period December 1978 through February 1994 was completed in September 1996. The data assimilation system, once defined, remained virtually constant throughout the period.

ERA has received assistance from the ECMWF Council, the European Community, the University of California, the Japan Meteorologcial Agency (JMA), the European Union (EU), the World Climate Research Project (WCRP), Cray Research Incorporated, and the Center for Ocean-Land-Atmosphere Studies (COLA). In addition data and co-operation have been forthcoming from many quarters, including ECMWF Member States, the University of Innsbruck, the National Ocean and Atmospheric Administration (NOAA) and National Center for Atmospheric Research (NCAR) in the United States of America, and the Australian Bureau of Meteorology (BoM).

Table of Contents

1. Introduction
2. Selection of a "best possible" assimilation system for reanalysis.
3. The ECMWF Reanalysis Data Assimilation System.
4. ERA Production
5. Observation Monitoring
6. Radiosonde Height Biases
7. TOVS Quality Control and Bias Tuning
8. Monitoring of Analysis Quality
9. Observing System Characteristics
10. Some General Circulation Features in ERA. Comparisons with ECMWF Operational Analyses.
11. ERA forecasts
12. Data for Research