Hourly elevation-adjusted PWV and modelled zenith transmittance at eight millimetre and submillimetre sites (2015–2025)

Processed hourly precipitable-water-vapour (PWV) and modelled zenith-transmittance series for seven Event Horizon Telescope sites and Delingha from 2015 to 2025. Atmospheric columns were derived at the adopted physical site elevations from ERA5 pressure-level temperature, specific humidity, geopotential, and contemporaneous ozone profiles and propagated through version 14.0 of the am atmospheric model. The release includes the complete hourly PWV and transmittance series, annual and monthly summaries, continuous-window persistence products, simultaneous-transparency statistics for Delingha and seven reference sites, representative spectra, three complete hourly-series figures, metadata, reproducibility scripts, and machine-readable quality-assurance reports. The radiative-transfer calculations include absorption by atmospheric gases; cloud liquid water, cloud ice, and precipitation are not included.