The Space Weather Prediction Center (SWPC) has issued a G3, or "strong," geomagnetic storm watch Friday through Sunday. SWPC rates these storms arriving from the sun on a scale of 1 to 5, with 1 being a minor storm and 5 an extreme storm.

The G3 geomagnetic storm watches are due to a pair of coronal mass ejections (CME) that are anticipated to arrive over the course of the next three days. A CME is an eruption of solar material. When they arrive at Earth, a geomagnetic storm can result. Watches of this duration and to this magnitude are infrequent, but not uncommon, according to SWPC.

The effects of a G3 storm are limited, SWPC said. A G3 geomagnetic storm may cause intermittent satellite navigation and low-frequency radio navigation problems. High-frequency radio also may be intermittently affected. The aurora has been seen as low as Illinois and Oregon.

The sun is the main source of space weather. Eruptions of plasma and magnetic field structures from sunspot regions, coronal mass ejections (CMEs), and solar flares can cause geomagnetic storms.

Storms are more common during solar maximums. The peak of sunspot activity is known as a solar maximum. The lull is known as solar minimum. Maximums and minimums occur on average in 11-year cycles. Earth is approaching the peak of the current solar maximum that began in 2020. The peak should occur in summer 2025.

Radio-frequency-disrupting flares reach Earth at the speed of light. CMEs travel more slowly, taking one to five days to reach Earth. Both can disrupt communications, the power grid, navigation, radio and satellite operations for minutes, hours or days at a time.

A complete loss of signal lock by a GPS receiver due to extreme noise from the upper atmosphere (primarily at night) can result in no location data for an interval of time. Noise introduced by the upper atmosphere could also induce errors in the calculated position.

Like during a thunderstorm, farmers can only manage through GPS-battering geomagnetic storms. If you know a storm is on the way, you can stop fieldwork and wait for the storm to pass. Or you could, like grandpa did, grab the steering wheel and just plow through, accepting crooked rows and any planting and data collection inaccuracies that follow.

But without GPS, the as-planted data (as-sprayed, as-fertilized) cannot be logged onto a map or georeferenced. This isn't just a negative result for farm operators -- seed suppliers and local agronomists rely upon these data for upstream use.

Here are specific actions farmers can take:

-- Understand what part of any equipment or data system relies on GPS or radio frequencies (RF) and how resilient that equipment is to RF/GPS noise. Are your GPS receivers single- or dual-frequency receivers? Single-frequency receivers are more susceptible to space weather.

-- Have a short-term local data backup system. Like a commercial security system that records everything and then deletes it after a certain period, data would go to both the cloud and a short-term, local backup system that could be recovered if the connection to the cloud is compromised.

-- Sign up for space weather alerts, watches and warnings at the NOAA Space Weather Prediction Center. (https://www.swpc.noaa.gov/…)

-- If an issue is noticed with the GPS systems, look at the NOAA alerts or the Navigation Centers civilian GPS outage reports (https://www.navcen.uscg.gov/…) to determine whether the source is environmental or a hardware problem.

-- If there is an elevated level of space weather and local hardware issues have been ruled out, report an outage to the Navigation Center through the online reporting: https://www.navcen.uscg.gov/…. It is important that the nation has a good understanding of how space weather affects users.

Dan Miller can be reached at dan.miller@dtn.com

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