GNSS Satellite Occultation Detection Applied to Radio Occultation

In the midst of growing worries about the energy, increasing demand for improved weather forecasting, and climate monitoring, the word is working to shift to sustainable energy sources and reduce the impacts of climate change. Simultaneously, the accuracy of weather forecasts and climate monitoring have become more crucial not only for energy efficiency but also for the environment preservation. The Global Navigation Satellite System (GNSS) Radio Occultation (RO) technique stands as well-suitable technique that provides measurements for observing the Earth’s atmosphere, as it is characterized with global coverage and high resolution. The concept of the occultation sounding uses a receiver placed on Low Earth Orbit (LEO) satellite to measure the Global Navigation Satellite System (GNSS) satellite’s observables, such as the atmospheric contribution of the signal along the limb in terms of a phase delay. These observables serve as essential insights that allow us to understand the atmosphere’s behavior. However, the GNSS receivers have limited onboard storage capacity. Therefore, it is important to precisely predict when the occultation event between the satellites occurs in a given day, so that the receiver can activate and record exclusively during the event. This study focuses first on evaluating the satellite’s visibility, then predicting the occultation events moments between LEO and GNSS satellites, and extracting the bending of the GNSS signal within the Earth’s atmosphere at these determined occultation events moments. The bending angles retrieved, as a result, empower us determining precise atmospheric profiles, ultimately enhancing our contribution to improved weather forecasting and climate monitoring.