Radio occultation atmospheric profiling from the Spire nanosatellite constellation and its impact on weather forecasting

Abstract

In a relatively short time, Spire has grown from a small start-up company to the largest commercial producer of satellite-based GNSS Earth observation products. The Earth observations produced with Spire’s GNSS science receiver include atmospheric profiles performed by radio occultation (RO) and space weather observations (slant total electron content (TEC) and scintillation indices) using signals from the GPS, GLONASS, QZSS, and Galileo constellations. Spire now produces thousands of RO profiles and millions of TEC observations each day with low latency, with plans for over 100 RO-producing satellites in the full constellation. Due to its agility and rapid launch cycle, averaging launches of four to eight satellites every six weeks, Spire has the unique ability to improve performance and add capabilities on-orbit that are impossible with traditional, risk-averse satellite missions. Spire has provided RO and space weather data to the second NOAA Commercial Weather Data Pilot program, the US Air Force Commercial Weather Data Pilot program, ESA, and numerous NWP centers and research institutions. Spire is also pioneering the provision of Earth observation data to NASA and ESA researchers through unique data purchase programs. In this talk, we will overview the status and capabilities of the Spire satellites and describe the collection of RO profiles from the GPS, GLONASS, Galileo, and QZSS constellations specifically for numerical weather prediction (NWP) applications. We will also describe precise orbit determination of our low Earth orbiting satellites and inversion of the RO profiles. We will show the statistical characteristics of our products, focusing primarily on bending angle and discussing the factors affecting the quality of the profiles. We will also present third-party evaluations of Spire RO data that highlight their quality and impact through assimilation on weather forecasting. Finally, we will outline our plans for expanding the Spire RO constellation in the future.