COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate)
COSMIC is a major international scientific program that operates constellations of small satellites to collect atmospheric data for meteorology, ionospheric research, and climate science. The program is a joint collaboration between the United States and Taiwan.
In the United States, the program is managed by the UCAR COSMIC Program, which is part of the University Corporation for Atmospheric Research (UCAR), a non-profit consortium of over 100 universities and colleges. UCAR is headquartered in Boulder, Colorado, USA. The primary U.S. partners are the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Space Force (USSF). The primary Taiwanese partner is the Taiwan Space Agency (TASA).
Continue…The core function of the COSMIC program is to use a technique called GNSS Radio Occultation (RO) to precisely measure the properties of Earth's atmosphere and ionosphere from space. This provides a continuous, global dataset that is critical for improving the accuracy of weather forecasts and for monitoring long-term climate change.
What the Entity Does
The COSMIC program designs, launches, and operates satellite constellations and manages the resulting data. Its activities are centered on providing high-resolution atmospheric "soundings" (vertical profiles) from all over the globe, particularly over oceans and remote areas where traditional weather balloons and ground stations are scarce.
The program's main technology, GNSS Radio Occultation (RO), works by using a satellite in low-Earth orbit (LEO) to "listen" to signals from Global Navigation Satellite System (GNSS) satellites (like the U.S. GPS, Europe's Galileo, etc.).
- As a GNSS satellite rises or sets on the horizon from the LEO satellite's perspective, its signal passes through the Earth's atmosphere.
- The atmosphere bends, slows, and slightly attenuates this radio signal.
- By measuring the precise change in the signal's bending angle and delay, scientists can calculate a highly accurate vertical profile of atmospheric properties, including temperature, pressure, density, and water vapor.
- The same signal is used to measure the electron density in the ionosphere, which is critical for space weather forecasting.
This technique is highly valued because it is extremely accurate, requires no calibration after launch, and provides uniform, all-weather data across the entire globe.
Key Missions
- COSMIC-1 (FORMOSAT-3): Launched in 2006, this was the original constellation of six satellites that proved the immense value of GNSS-RO data for operational weather forecasting. It provided thousands of atmospheric profiles per day and was retired in 2020.
- COSMIC-2 (FORMOSAT-7): This is the next-generation, six-satellite constellation launched in 2019. It is equipped with more advanced receivers that can track signals from multiple GNSS constellations, dramatically increasing the quantity (providing over 5,000 profiles per day) and quality of data, especially in the tropical regions which are critical for hurricane formation.
Products and Services
The "products" of the COSMIC program are its scientific datasets, which are processed and distributed to the global scientific and operational community. The primary "service" is the COSMIC Data Analysis and Archive Center (CDAAC), operated by UCAR, which provides open and timely access to this data.
These products are essential for operational agencies like NOAA (for weather models) and the U.S. Space Force (for space weather) as well as the international research community.
1. Neutral Atmosphere Data Products
These products profile the atmosphere from the surface up to the stratosphere (approx. 40-60 km). They are the primary data used in numerical weather prediction (NWP) models.
- Atmospheric Profiles ("atmPrf"): This is the core data product. It provides high-resolution vertical profiles (typically 100-200m resolution) of:
- Bending Angle
- Refractivity
- Retrieved Profiles ("wetPrf" & "dryPrf"): These are profiles of the key physical variables derived from the refractivity data.
- Temperature: Highly accurate temperature profiles used for climate monitoring and weather models.
- Water Vapor (Humidity): Critical data for tracking atmospheric rivers and predicting storm formation and intensity.
- Pressure & Density: Foundational data for weather models.
- Gridded NWM-ready Products: Processed data that is formatted for direct assimilation into major numerical weather prediction models, significantly improving their accuracy.
2. Ionosphere Data Products
These products measure the state of the ionosphere, the electrically charged upper layer of the atmosphere. This is crucial for space weather, which can disrupt satellite operations, GPS navigation, and radio communications.
- Ionospheric Profiles ("ionPrf"): Provides high-resolution vertical profiles of:
- Electron Density: A precise measurement of the ionosphere's "charge" from the satellite's altitude (approx. 520-550 km) down to the lower ionosphere.
- Total Electron Content (TEC): This product measures the total number of electrons in a column between the GNSS satellite and the COSMIC receiver, providing a 2D map of ionospheric activity.
- Scintillation Indices ("scinPrf"): These products measure the "turbulence" in the ionosphere. High scintillation can severely disrupt or block GPS and communication signals, and COSMIC-2 provides critical data on these events, especially in the volatile equatorial regions.
3. Data Support Services
- COSMIC Data Analysis and Archive Center (CDAAC): The UCAR-run portal that provides open access to all COSMIC-1 and COSMIC-2 data products. It offers both near real-time (NRT) data for operational forecasting and post-processed data for scientific research.
- Data User Support: The COSMIC program office provides documentation, user guides, forums, and technical support to help researchers and agencies utilize its data products effectively.
