- Telephone maps outperform traditional Klobuchar ionospheric model globally
- Underserved regions like Africa benefit from improved ionosphere data
- Geomagnetic storms are tracked with great precision using smartphone networks
Mapping the ionosphere is essential for improving the accuracy of navigation systems, but existing methods face significant limitations. Although ground-based GNSS stations provide detailed maps of the total electron content (TEC) of the ionosphere, their coverage is patchy, leaving large gaps in underserved regions.
Today, researchers from Google Research, Mountain View, California, USA, demonstrated an innovative solution using millions of Android smartphones as a distributed network of sensors in a study published in Nature.
Although less precise than traditional instruments, these devices effectively double measurement coverage, providing precise data about the ionosphere and addressing long-standing infrastructure disparities.
The influence of the ionosphere on navigation
The ionosphere, a layer of ionized plasma extending from 50 to 1,500 km above Earth, has a significant impact on Global Navigation Satellite System (GNSS) signals by introducing positioning errors. However, traditional ground GNSS stations, while accurate, suffer from limited spatial coverage and leave underserved regions vulnerable to inaccuracies.
The Google Research study capitalizes on the billions of smartphones equipped with dual-frequency GNSS receivers to fill coverage gaps. Unlike traditional GNSS stations, smartphones are mobile, widely distributed, and capable of capturing large amounts of data.
By aggregating and averaging measurements from millions of devices, researchers achieved accuracy comparable to that of dedicated monitoring stations, even resolving phenomena such as solar storms and plasma density structures.
Android’s GNSS API facilitated the collection of satellite signal data, such as travel times and frequencies, which was then used to estimate the total electron content (TEC) of the ionosphere.
The study showed that although individual measurements from phones are noisier than those from monitoring stations, their collective data provides robust and reliable results.
The comparisons showed that the phone-based TEC model outperformed existing methods like the Klobuchar model, which is widely used in mobile phones.
Using data from Android phones, researchers doubled the measurement coverage of the ionosphere compared to traditional methods and were able to map plasma bubbles over India and South America as well as the increased storm density over North America during a geomagnetic storm in May 2024.
They also observed midlatitude troughs over Europe and equatorial anomalies – a phenomenon previously inaccessible due to poor station coverage.
Notably, regions like India, South America, and Africa, often underserved by traditional monitoring networks, have benefited significantly from this approach, which has produced real-time, high-resolution TEC maps.
