The Data Assimilation System and Initial Performance Evaluation of the ECMWF Pilot Reanalysis of the 20th-Century Assimilating Surface Observations only (ERA-20C)

Poli, Paul ; Hersbach, Hans ; Tan, David ; Dee, Dick ; Thépaut, Jean-Noël ; Simmons, Adrian ; Peubey, Carole ; Laloyaux, Patrick ; Komori, Takua ; Berrisford, Paul ; Dragani, Rossana ; Trémolet, Yannick ; Holm, Elias ; Bonavita, Massimo ; Isaksen, Lars ; Fisher, Mike