ERA-20C is a climate reanalysis dataset covering the period 1900 to 2010.
ERA-20C assimilates observations of surface pressure and surface marine winds only. It is an outcome of the ERA-CLIM project.
For further details please see the ECMWF product page.
Currently there are no known issues with ERA-20C.
Data is archived at ECMWF and available for download from ECMWF data services.