How Geomagnetic Storms and Ionospheric Activity Affect GNSS Performance

GNSS positioning accuracy depends not only on receiver performance and algorithms, but also on space weather conditions. During periods of strong solar activity—especially geomagnetic storms—GNSS users may experience reduced accuracy, signal instability, or even temporary positioning interruptions.

Understanding how geomagnetic storms and ionospheric activity affect GNSS performance can help users better plan operations and mitigate potential risks, particularly in high-precision applications.

What Is a Geomagnetic Storm?

Geomagnetic storms are caused by intense solar events such as Coronal Mass Ejections (CMEs). When a CME is directed toward Earth, it ejects large amounts of charged solar particles into near-Earth space. In some cases, these events form a so-called “full halo” CME, indicating that the ejection is widespread and likely to interact strongly with Earth’s magnetic field.

When these charged particles reach Earth, they disturb the planet’s magnetosphere and upper atmosphere, triggering geomagnetic storms that can last for hours or even days.

Why Geomagnetic Storms Impact GNSS

The main reason geomagnetic storms affect GNSS is their influence on the ionosphere—a layer of Earth’s upper atmosphere located roughly 50 to several hundred kilometers above the surface.

The ionosphere contains a high concentration of charged particles created by solar radiation. During geomagnetic storms or periods of high solar activity, the density and distribution of these charged particles can change rapidly, leading to abnormal signal behavior.

For GNSS users, these disturbances can cause:

• Increased positioning errors
• Signal instability or loss of lock
• Degraded performance in high-precision applications such as RTK and PPP

Solar Activity Cycles and Ionospheric Variations

Ionospheric activity follows the well-known 11-year solar cycle, which is driven by periodic changes in solar radiation and magnetic activity. The current solar cycle is expected to peak between 2024 and 2026, meaning increased ionospheric disturbances are more likely during this period.

In general, ionospheric activity is stronger at low latitudes, especially near the equator. As a result, GNSS users operating in equatorial regions may experience more pronounced positioning degradation during periods of high solar activity.

How Ionospheric Activity Affects GNSS Signals

Ionospheric disturbances influence GNSS signals in several key ways:

Signal Delay

As GNSS signals pass through the ionosphere, they experience a delay caused by the charged particles. This delay affects the signal travel time calculation and can introduce positioning errors if not properly corrected.

Frequency Dispersion

Different GNSS frequencies propagate through the ionosphere at slightly different speeds. This dispersion can distort carrier phase measurements and reduce positioning accuracy, particularly for single-frequency receivers.

Signal Scintillation

Ionospheric scintillation refers to rapid fluctuations in signal amplitude and phase caused by small-scale irregularities in the ionosphere. Scintillation is more common in equatorial and high-latitude regions and can lead to signal loss, tracking instability, or increased measurement noise.

Enhanced Disturbance During Geomagnetic Storms

During geomagnetic storms, ionospheric disturbances become more intense. Higher electron density and stronger irregularities can significantly degrade GNSS signal quality, occasionally resulting in temporary service interruptions or reduced positioning reliability.

How to Reduce the Impact of Ionospheric Activity

Although ionospheric disturbances cannot be avoided, their impact on GNSS positioning can be effectively reduced by applying proper system and configuration strategies:

Use Dual-Frequency or Triple-Frequency GNSS

Multi-frequency GNSS receivers can estimate and correct ionospheric delays by comparing signals at different frequencies, significantly improving positioning accuracy under disturbed conditions.

Enable Multi-Constellation Tracking

Tracking satellites from multiple GNSS constellations—such as GPS, Galileo, BeiDou, and GLONASS—increases satellite availability and observation redundancy, improving robustness during ionospheric disturbances.

Optimize Satellite Elevation Mask

Setting a higher satellite elevation mask (for example, 10 degrees or above) reduces the influence of low-elevation signals, which are more affected by ionospheric delay and multipath effects.

Keep Firmware and Algorithms Updated

Modern GNSS firmware and positioning algorithms are continuously optimized to handle challenging ionospheric conditions. Keeping receivers updated ensures the best possible performance during periods of high solar activity.

Practical Takeaway for GNSS Users

Geomagnetic storms and ionospheric activity are natural phenomena that can temporarily degrade GNSS performance—especially for high-precision positioning applications. By understanding these effects and adopting appropriate mitigation strategies, users can maintain more reliable and stable positioning even during periods of strong solar activity.

As GNSS technology evolves, multi-frequency, multi-constellation receivers combined with advanced algorithms will continue to play a key role in minimizing space-weather-related positioning risks.