Decoding Radio Occultation, the cornerstone of accurate weather forecasting

As the demand for accurate and high-resolution forecasts grows, innovative technologies like Radio Occultation (RO) are stepping into the spotlight, revolutionizing how we observe and predict Earth’s atmosphere.

Originally developed by scientists in 1965 to study the temperature and pressure on Mars, RO now helps to improve weather prediction on both a global and local scale, as well as proving a pivotal tool for Earth climate studies.

What is Radio Occultation?

Radio Occultation (RO) is an advanced remote sensing technique that uses signals from Global Navigation Satellite Systems (GNSS) to measure critical atmospheric variables such as temperature, pressure, and water vapor. These measurements are obtained by tracking how GNSS signals bend as they pass through different layers of the atmosphere from the planetary boundary layer to the top of the stratosphere. The data collected by Spire’s low-Earth orbit satellites offers unparalleled vertical resolution and long-term stability, making RO a cornerstone for improving weather forecasts and monitoring climate change.

How Spire is transforming Radio Occultation

Spire Global has emerged as a leader in RO technology, deploying the world’s largest commercial GNSS-RO constellation. Utilizing nanosatellites equipped with proprietary STRATOS receivers, Spire delivers thousands of high-quality RO atmospheric profiles daily. This remarkable output exceeds many publicly funded missions, such as COSMIC-2*, and offers a similar level of quality to these missions. Spire’s achievement represents a breakthrough in scalability and efficiency, providing critical atmospheric data to enhance weather forecasting and climate research.

*COSMIC-2, a publicly funded satellite mission managed by NOAA, provides global atmospheric data through GNSS Radio Occultation, supporting weather forecasting, climate monitoring, and space weather research with high-quality profiles from six advanced satellites.

Key advancements of Spire’s technology include:

• Multi-constellation tracking: Spire’s receivers can track signals from GPS, GLONASS, Beidou, and Galileo satellites, doubling the profile collection rate compared to older systems
• Cost-efficient nanosatellites: Compact satellites reduce production costs while maintaining high performance, enabling rapid deployment and innovation
• Global coverage: With satellites in diverse orbits, Spire achieves comprehensive geographic and temporal coverage, vital for both weather forecasting and climate studies

The impact of RO on weather forecasting

RO data plays a critical role in improving Numerical Weather Prediction (NWP) models. Studies show that assimilating Spire’s RO profiles into weather models significantly enhances forecast accuracy, especially for extreme weather events. During the early stages of the COVID-19 pandemic, when aircraft-based observations plummeted, Spire’s RO data filled critical gaps, supporting reliable forecasts.

For example, integrating Spire’s data has been shown to:

• Improve short- and medium-range weather forecasts
• Enhance predictions of hurricane paths and intensities
• Provide consistent benchmarks for monitoring climate trends over decades

Spire’s RO data ranks among the most impactful data sources for enhancing weather forecasting metrics globally after microwave radiance and infrared data, according to sources such as ECMWF and NASA.

“Accurate and reliable weather forecasts are crucial to cope with the impacts of weather hazards and climate change and to help businesses thrive; these forecasts depend on high-quality observations of the atmosphere. Spire’s impressive satellite constellation provides important observations across the globe that enhance our forecasting capability,” Alan Thorpe, of the UK Met and a Scientific Advisor and Spire Global Board Member, said.

Spire’s RO data and additional datasets from its satellite constellation, combined with other data sources, feed into Spire’s proprietary weather prediction models, including the Spire High-Resolution Forecast, the backbone for many of Spire’s weather products.

Pioneering possibilities

Spire’s innovation doesn’t stop at traditional RO. The company is exploring exciting new applications of GNSS-RO, Reflectometry, and Hyperspectral Microwave, including:

• Polarimetric RO: Detecting ice clouds and liquid precipitation, estimating precipitation intensity, and monitoring cloud properties (e.g., thickness and altitude) by separately measuring the GNSS signal polarization components (horizontal and vertical)
• Grazing angle GNSS-R: Leveraging reflected GNSS signals to measure sea ice thickness, ocean winds, and soil moisture, enabling large-scale monitoring for agriculture, drought assessment, and hydrological studies among other industry and weather prediction enhancement applications
• Hyperspectral Microwave: Observing the Earth in multiple microwave frequency bands, capturing detailed atmospheric measurements, including water vapor and temperature
• Ionospheric observations: Real-time monitoring of the ionosphere to mitigate disruptions in GNSS-based navigation and communication

Future collaborations, such as the Radio Occultation Modeling Experiment (ROMEX), aim to quantify the impact of large-scale RO data assimilation further, setting new standards for forecasting and climate research. ROMEX is a collaborative initiative led by the International Radio Occultation Working Group (IROWG) to advance global weather and climate forecasting by improving the use of Radio Occultation data in Numerical Weather Prediction models. A key focus of ROMEX is determining how much RO data is sufficient to generate the most accurate forecasts, ensuring optimal integration into weather prediction models.

Leveraging RO data for weather prediction and research

Radio Occultation is more than just a technology; it is a transformative tool for understanding and predicting our planet’s complex systems. By enhancing weather forecasts, mitigating climate risks, and supporting groundbreaking scientific research, RO is paving the way for a safer, more sustainable future. Spire Weather & Climate integrates this powerful data into every product, delivering unmatched precision and insights for businesses.

Whether you’re a business reliant on accurate forecasts or a researcher delving into climate phenomena, now is the time to harness the power of RO. Spire Global invites you to explore how its cutting-edge data solutions can empower your mission and make a lasting impact.

Learn more about how Spire’s Radio Occultation capabilities can elevate your weather intelligence and business operations.