Received an email from Eric, a good SAR friend, who told me that last week he witnessed some of the most spectacular northern lights (aurora borealis) he has ever seen. When I was last in Iceland, working with some of the SAR teams there, I was fortunate to see them for myself and they are mesmerizing to look at. Later in Antarctica I was lucky enough to observe them again; here they are called the aurora australis.
They are caused by particles from the sun blowing toward the earth with the solar wind. When these particles hit the earth’s magnetic field, the crash of atoms and molecules create these lights and generally the stronger the electrical storm the more magnificent the lights.
So I pinged Mike C at the Space Weather Laboratory at NASA’s Goddard Space Flight Centre to ask him if these had been big storms and if they had affected the GPS constellation, as previous storms have been quite disruptive affecting HF communications and GPS signals.
The storm, he informed me, was the strongest since the fall of 2003 yet had a limited effect on GPS receivers and users. It began on January 22 and had been forecast by the National Oceanic and Atmospheric Administration (NOAA) who issued warnings to the military and civil aviation.
The reason its affects were limited were because the storm struck the Earth’s atmosphere at an angle, rather than a direct hit, so the effects were weaker.
Space weather affects GNSS in three ways:
- TEC (total electron content) – causes delays in the code measurements and creates inaccurate readings for receivers.
- Scintillation – causes variations in signal power, sometimes completely blocking signals.
- Solar bursts – creates lots of energy which degrades GNSS signals and significantly decreases accuracy.