Global Summary of Day (GSOD) (NOAA National Data Center (NNDC) Climate Data Online (CDO)) (Includes GSN data submitted by GTS but not by countries) (Synoptic Data) (Contact: Neal Lott)
Global Historical Climatology Network Daily (GHCN-Daily)(Global surface station historical data including GSN data) (GTS and country supplied data) (C-flag and G-flag: Country supplied data (takes precedent over International Collection)) (I-flag: International Collection (supplied from undocumented sources) (takes precedent over Synoptic Data)) (S-flag: Synoptic data (source: GSOD)) (Contact: Matthew Menne)