COSMIC - Constellation Observing System for Meteorology

COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) is a joint US-Taiwan scientific satellite program operated by UCAR (University Corporation for Atmospheric Research) in Boulder, Colorado, in partnership with Taiwan's NSPO (National Space Organization). COSMIC represents the most operationally significant GPS radio occultation (GNSS-RO) constellation in history, providing a globally distributed daily stream of atmospheric temperature, pressure, humidity, and ionospheric electron density profiles from LEO.

The original COSMIC-1 constellation of six satellites launched in April 2006 and operated through approximately 2020, demonstrating at large scale that GNSS-RO data dramatically improved numerical weather prediction. Studies by NOAA, ECMWF, and national meteorological services quantified 5–10% improvements in forecast skill globally — large improvements in a field where 1% matters — particularly for Southern Hemisphere and marine observations where radiosonde coverage is sparse. COSMIC-1 produced approximately 2,000 daily occultations, providing the first operationally significant non-radiosonde global atmospheric sounding data stream.

COSMIC-2 (also known as FORMOSAT-7), launched June 2019 aboard a SpaceX Falcon Heavy, expanded to six satellites in a tropical/mid-latitude orbit (24° inclination) plus two higher-inclination demonstration satellites. COSMIC-2 uses improved TGRS (Tri-GNSS Radio Occultation System) receivers that track GPS, GLONASS, and Galileo signals simultaneously, generating 5,000–7,000 daily soundings with sub-km vertical resolution in the troposphere — a 3–4x increase over COSMIC-1 in tropical coverage critical for hurricane forecasting and tropical cyclone track prediction.

COSMIC data is provided free of charge to the global meteorological community through UCAR's CDAAC (COSMIC Data Analysis and Archive Center), making it one of the most widely used satellite datasets in operational weather forecasting. Over 60 national weather prediction centers assimilate COSMIC-2 data into their models. The program's success directly motivated commercial GNSS-RO providers including Spire Global, PlanetIQ, and GeoOptics, which now supply commercial RO data to NOAA under Commercial Weather Data Pilot contracts.