Site (station location) Boulder, CO, United States Instrument Type Sonde Parameter Ozone Model ECC Instrument Status Active Periods of Activity 1991 –present Cooperating Institutions NOAA/ESRL Data Link Ames Metadata File https://www-air.larc.nasa.gov/pub/NDACC/PUBLIC/meta/o3sonde/Boulder_Hilo_SPole_Samoa_o3snd_pc_2025.pdf M&A Directory Entry B. Johnson (NOAA/ESRL) — Weekly ECC sondes since June 1991.