GHCN-Daily: yearly CSV versus station .dly records

GHCN-Daily has more than one file layout. Choose the documentation for the representation you downloaded rather than applying one parser to every file. The yearly CSV documentation describes comma-separated fields in this order: station identifier; date in YYYYMMDD form; element; data value; measurement flag; quality flag; source flag; observation time. The observation-time field uses an hour-minute representation. Element units and flag meanings are described in section III of the main README. [S1] A station .dly record instead begins with an 11-character station identifier, four-character year, two-character month and four-character element. It then contains a value and three flags for each of the 31 day positions. The first day's value occupies columns 22–26 in the published one-based layout. [S2] Practical check: inspect the file's structure before parsing. A station identifier followed by commas is not the same layout as a fixed-width monthly record. Preserve flags separately from values, and retain the exact README version used for interpretation. That checklist is an editorial recommendation, not an additional NOAA field specification. Additional source notes The README uses -9999 for a missing daily value. It also specifies how positions beyond the end of a shorter month are filled. Treat those positions as missing rather than additional observations.