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TM2

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NREL Typical Meteorological Year v2.

At a glance
Original creator National Renewable Energy Laboratory (NREL)
Purpose Typical Meteorological Year, version 2: a year of hourly weather for one US station drawn from the 1961 to 1990 record, in fixed-width text.
Extensions .tm2
Poka parser poka-tm2
Viewer poka-table-viewer
Depth tier Parser with a shared viewer (see Depth tiers)
Breadth tier B4 Summary (see Breadth tiers)

How much Poka reads

B4 Summary. The container and metadata are read and summarised (counts, properties, structure), but the main content is not rendered.

Confidence: high (the reviewer read the code and a test that proves the claim). Basis: Reviewed 2026-10-16: poka-tm2 src/lib.rs (FIELDS table of 10 fixed-width fields, parse_tm2, build_ast, unit tests) and tests/samples.rs; corpus web-12839.tm2 and web-12839-lf.tm2 (Miami, LF and CRLF variants) plus the 12-byte SANKOM Temp.TM2 stub, which is refused by name. TMY2 fixed-width only. Rows are reduced to a monthly table plus a Year row; no hourly row is shown.

What Poka does not read

  • individual hourly values (the hourly table is never rendered)
  • direct normal and diffuse horizontal irradiance, total sky cover, pressure and wind direction are read and accumulated but not shown
  • extraterrestrial radiation and illuminance fields
  • opaque sky cover, visibility, ceiling height and present weather
  • precipitable water, aerosol optical depth, snow depth, days since last snowfall and liquid precipitation
  • source and uncertainty flags (only the missing-value flag is used)
  • SANKOM Audytor .TM2 error stub is recognised but not read

Background

TMY2 is the second TMY edition, from 239 stations, and the predecessor of TMY3 (Wikipedia). A file has one header line and 8,760 fixed-width rows of 142 characters. Every numeric field is a zero-padded integer in scaled units: a dry-bulb temperature of 0200 means 20.0 °C. Each value also carries a source flag and an uncertainty flag, and a source of ? means the value is missing. Poka applies the scaling and shows each month's source year and a monthly summary table; no hourly row is shown. SANKOM Audytor writes an unrelated 12-byte .TM2 error stub; Poka names it and declines to read it as weather.

Versions

Version Identifier Poka Note
TMY2 fixed-width Partly read All rows are read, but only a monthly summary is shown; direct normal and diffuse radiation, sky cover, pressure and wind direction are accumulated and never shown.

Libraries

Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.

  • tim2-rs (candidate; MIT; Rust; https://github.com/travistrue2008/tim2-rs) — Image loader for TIM2 (.tm2) files; language inferred from Cargo.toml; commit dates not visible, an earlier search listing suggested last release around 2020.

Sources