Global Navigation Satellite System Radio Occultation (GNSS-RO) has become one of the most valuable data sources for modern weather forecasting, climate monitoring, and space domain awareness. Its ability to deliver high-accuracy, all-weather, globally distributed atmospheric profiles makes it essential for numerical weather prediction (NWP) and increasingly for AI-driven forecasting systems.

As the ecosystem matures, both commercial providers and government missions play important roles in the global observing system. Below is a ranking of the five top sources of GNSS-RO data, both commercial and government.

#1. PlanetiQ: The Gold Standard for GNSS-RO Data

Best for: Operational forecasting, defense, and high-resolution atmospheric modeling

PlanetiQ leads the field by combining global coverage, high precision, and unmatched data volume in a single system, delivering unmatched performance across every key metric:

Strengths

Pole-to-pole global coverage of both atmosphere and ionosphere
Highest vertical resolution in the industry
Highest precision and signal-to-noise ratio (SNR) (1500+v/v)
Routine profiling down to the surface, including the lower troposphere and boundary layer
Over 7,000+ high-quality atmospheric profiles per day with continued growth planned
Multi-GNSS capability: GPS, GLONASS, Galileo, BeiDou
Total Electron Content (TEC) data rated “best-in-class” by NASA for space weather applications

Limitations

As a commercial provider, long-term data continuity can depend on government and customer funding cycles

Bottom line:
PlanetiQ is currently the most complete GNSS-RO data provider, delivering the best combination of coverage, resolution, precision, and scale for operational use.

#2. COSMIC-2: A Proven Government Benchmark

Best for: Research and equatorial observations

COSMIC-2 (FORMOSAT-7) has long been considered a benchmark mission for GNSS-RO data quality.

Strengths

High-quality, well-characterized atmospheric profiles
Deep integration into global weather models
Open and freely available data for the research community

Limitations

Primarily equatorial coverage, not truly global
The constellation is aging, with no confirmed follow-on mission

Bottom line:
COSMIC-2 remains an important reference dataset, but its limited coverage makes it insufficient on its own for global operations.

#3. Spire Global: Accessible Commercial Data at Scale

Best for: Data volume and commercial accessibility

Spire Global operates a large CubeSat constellation that provides GNSS-RO data to a wide range of customers.

Strengths

Produces >3,000 atmospheric profiles per day
Consistent and commercially available data stream
Broad adoption across weather and climate applications

Limitations

Lower signal-to-noise ratio compared to premium systems
Less penetration into the lowest atmospheric layers
Satellites designed with limited propulsion for station keeping leads to short lifespan

Bottom line:
Spire offers strong data availability and accessibility, but with tradeoffs in precision and vertical performance.

#4. MetOp: Europe’s Operational GNSS-RO Backbone

Best for: Operational meteorology and long-term climate records

The MetOp satellite series provides GNSS-RO data through the GRAS (GNSS Receiver for Atmospheric Sounding) instrument.

Strengths

True polar coverage, enabling strong high-latitude sampling
Long-term continuity for climate monitoring
Proven reliability and operational heritage
Publically available

Limitations

Lower data volume than newer commercial constellations (approximately 1000 profiles a day)
Less dense global sampling

Bottom line:
MetOp remains a trusted government system, particularly valuable for climate continuity and polar coverage.

The next-generation MetOp-SG (launched August 2025) with the GRAS-2 instrument is expected to significantly increase performance, with up to ~2,000 profiles per day per satellite once fully operational.