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What’s New: A paper by RNT Foundation member Hexagon NovAtel.

Why It’s Important: Solar activity is always a concern to GPS/GNSS users. The sun is moving toward solar maximum estimated for the summer of 2025. 

What Else to Know:

  • While significant solar activity can and has occurred at any point in the solar cycle, it is more likely around the times (a year before and a year after) of solar maximums.
  • Many scientists believe this will be a relatively quiet solar maximum. DR Scott McIntosh, Deputy Director of the National Center for Atmospheric Research, though, believes it will be much more active than normal.  He has gone against the consensus before and been right.


What is ionospheric activity and how do I mitigate against the impact on GNSS?

What is ionospheric activity?

The ionosphere is part of the Earth’s atmosphere located between 50 to 1000 km above the Earth’s surface. This layer contains free electrons, especially at altitudes between 250 to 400 km, that can adversely affect the performance of GNSS receivers.

We are currently within a period of increased ionospheric activity. As a result, more frequent and greater adverse effects to GNSS tracking and positioning can be expected at certain times and in certain environments.

Ionospheric activity is influenced by the periodic cycles of solar activity, the Earth’s tilt/orbit (annual), the Earth’s rotation (daily), as well as interaction with the Earth’s magnetic field. Increased ionospheric activity is correlated with the following factors.

  • Sunspot Activity: Increased sunspot activity, which is linked to the 11-year solar cycle. The sunspot count can be monitored on websites such as the NOAA Space Weather Prediction Center. The chart below illustrates the measured (black line) and predicted (red line) sunspot activity for the current solar cycle 25.