As a geospatial professional, you spend your days analyzing the ground beneath your feet—mapping topographies, scanning infrastructure, and ensuring every single data point is anchored in absolute reality. But sometimes, the biggest threat to your accuracy doesn’t come from the terrain, the heat, or the hardware. It comes from 93 million miles away.
We are currently navigating Solar Cycle 25, a period of intense solar activity that is heavily impacting the high-precision equipment our industry relies on. If your crews have been experiencing unexplained RTK dropouts, sudden jumps from a tight “Fix” to a useless “Float,” or frustratingly slow initialization times, user error might not be the culprit. You might be experiencing the very real effects of space weather.
Here is what every surveyor and 3D laser scanning professional needs to know about how solar flares disrupt GNSS signals—and how to keep your projects on track when the sun refuses to cooperate.
The Science: How Space Weather Scrambles GNSS Signals
To understand the problem, we have to look at the journey of a GNSS signal. Positioned roughly 20,000 kilometers above the Earth, GNSS satellites broadcast radio signals down to your rover. Under normal conditions, these signals travel smoothly through the vacuum of space and the Earth’s atmosphere. MDPI
However, when the sun emits a solar flare or a Coronal Mass Ejection (CME), it blasts the Earth with high-energy radiation and charged particles. When these particles hit the Earth’s upper atmosphere—specifically the ionosphere (the layer roughly 50 to 1000 km above us)—they severely disrupt the electron density.
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This creates two major headaches for surveyors:
- Total Electron Content (TEC) Delay: As the ionosphere becomes highly charged, the GNSS signal actually slows down as it passes through the atmosphere. Because GPS calculates position based on the exact time it takes a signal to reach your receiver, any unexpected delay translates directly into positioning errors.
- Ionospheric Scintillation: This is the most destructive effect for high-precision surveying. Scintillation refers to rapid, localized fluctuations in the amplitude and phase of radio waves. Imagine looking at a coin at the bottom of a fast-moving, turbulent river; the image warps, dances, and breaks apart. Scintillation does the exact same thing to GNSS radio signals.
What a Disruption Looks Like in the Field
How do you know if you are dealing with a solar event rather than a bad battery or local multipath interference?
During a severe geomagnetic storm—such as the massive G5 storm that made headlines in May 2024—the disruptions are impossible to ignore. Geospatial professionals globally reported severe “noise” in their position solutions.
If a solar storm is interfering with your network, your field crew will likely experience:
- Loss of Tracking Lock: The receiver physically cannot track the degraded satellite signals, causing constant cycle slips.
Trimble Positioning Services - Degraded Corrections: Base stations struggle to maintain an accurate stream to the rover.
Trimble Positioning Services - Fix to Float Drops: The system will repeatedly drop out of an RTK-fixed operation, reducing your accuracy from sub-centimeter to decimeters or worse.
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Forecasting the Unseen: Why NOAA is Your Best Friend
You wouldn’t send a scanning crew out without checking the weather for rain. During Solar Cycle 25, you should apply that same logic to space weather.
The National Oceanic and Atmospheric Administration (NOAA) operates the Space Weather Prediction Center (SWPC), which utilizes a fleet of satellites to monitor solar wind and CMEs in real-time. By checking space weather forecasts, you can predict when GNSS disruptions are most likely to occur.
What to look for:
- The Kp Index: This is the global geomagnetic storm index, ranging from 0 to 9. A Kp index of 1-3 means calm skies. A Kp index of 5 or higher indicates a geomagnetic storm. If the Kp is high, expect your GNSS network to struggle.
- Time of Day: Scintillation is a highly dynamic phenomenon, but it is often most severe around sunset and the hours immediately following dusk. If a storm is active, try to schedule highly sensitive RTK tasks for the early morning.
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The Backup Plan: How to Pivot When GNSS is Down
We can’t control the sun, but we can control how our field crews respond. When a geomagnetic storm takes your GNSS network offline, grinding the job to a halt is not an option. Here is how Topo Element and other top-tier survey teams mitigate the damage:
1. Leverage Multi-Frequency Equipment and Advanced Firmware
If you are running older single-frequency receivers, you will bear the brunt of solar storms. Modern multi-constellation, multi-frequency receivers are much more resilient. Because ionospheric delays affect different radio frequencies in different ways, a multi-frequency receiver can compare the differences between the L1, L2, and L5 bands to mathematically calculate and remove the ionospheric error. Furthermore, firmware upgrades from major manufacturers (like Trimble’s IonoGuard) are specifically designed to detect and filter out scintillation noise.
2. Tighten Your Baselines
The further your rover is from the base station, the more differently the ionosphere will affect the two locations. During periods of high solar activity, shorten your baselines to ensure the base and rover are looking through the exact same patch of disturbed atmosphere.
3. Pivot to Optical Total Stations and Terrestrial 3D Laser Scanning
This is where having a diverse technological toolkit pays off. Solar flares only impact satellite-based radio signals. They have absolutely zero effect on terrestrial optical instruments.
When the Kp index spikes and GNSS drops to “Float,” a well-equipped crew will immediately pivot. By bringing in localized control points with a robotic Total Station and capturing the site with 3D Terrestrial Laser Scanning (LiDAR), you can continue collecting millimeter-accurate data completely independent of the sky. Laser scanning relies on time-of-flight light pulses interacting with physical objects directly in front of you—meaning space weather is entirely removed from the equation.
The Bottom Line
Solar Cycle 25 will continue to bring unpredictable space weather for the next few years. By educating your field crews, monitoring NOAA’s forecasts, and ensuring your team is cross-trained on optical and 3D laser scanning alternatives, you can ensure that the only thing a solar flare ruins is the radio reception in the company truck.
Check out this brief explainer on Solar Flares and GPS Accuracy to see a visual breakdown of how the ionosphere affects signal transmission.