The first reanalysis product, ERA-15, generated re-analyses for approximately 15 years, from December 1978 to February 1994. The second product, ERA-40 (originally intended as a 40-year reanalysis) begins in 1957 (the International Geophysical Year) and covers 45 years to 2002. As a precursor to a revised extended reanalysis product to replace ERA-40, ECMWF released ERA-Interim, which covers the period from 1979 to present. A new reanalysis product ERA5 has recently been released by ECMWF as part of Copernicus Climate Change Services. This product has higher spatial resolution (31 km) and covers the period from 2010 to 2016.
In addition to re-analysing all the old data using a consistent system, the reanalyses also make use of much archived data that was not available to the original analyses. This allows for the correction of many historical hand-drawn maps where the estimation of features was common in areas of data sparsity. The ability is also present to create new maps of atmosphere levels that were not commonly used until more recent times.
Accessing the dataEdit
The data can be downloaded for research use from ECMWF's homepage (see external links) and the National Center for Atmospheric Research data archives. Both require registration. A Python web API can be used to download a subset of parameters for a selected region and time period.
- NCEP/NCAR Reanalysis - NCEP/NCAR re-analyses