Solar flares disrupted radio communications during 2017 hurricane relief effort

“Space weather and Earth weather aligned to heighten an already tense situation in the Caribbean,” said Rob Redmon, a space scientist with NOAA’s National Centers for Environmental Information in Boulder, Colorado, and the lead author of the new study. “If I head on over to my amateur radio operator, and they have been transmitting messages for me, whether it be for moving equipment or finding people or just saying I’m okay to somebody else, suddenly I can’t do that on this day, and that would be pretty stressful.”

Bobby Graves, an experienced ham radio operator who manages the Hurricane Watch Net from his home near Jackson, Mississippi, said the flares caused communications to go down for hours. The Hurricane Watch Net is a group of licensed amateur radio operators trained and organized to provide communications support to the National Hurricane Center during storm emergencies.

“You can hear a solar flare on the air as it’s taking place. It’s like hearing bacon fry in a pan, it just all of a sudden gets real staticky and then it’s like someone just turns the light completely off, you don’t hear anything. And that’s what happened this last year on two occasions,” Graves said. “We had to wait ‘til the power of those solar flares weakened so that our signals could actually bounce back off the atmosphere. It was a helpless situation.”

The new study detailing the activity on the Sun and its effects on radio communications from 4-13 September serves as an overview to a collection of journal articles in Space Weather investigating the solar activity of September 2017. The collision of Earth and space weather in September delivered a reminder that solar events can happen at any time and may coincide with other emergencies, according to the study’s authors.

The information in the study could help scientists improve space weather forecasting and response, according to the study’s authors. By understanding how the events on the Sun and Earth unfolded, scientists can better understand how to forecast and prepare for future events, they said.

The new study shows the solar flares affected shortwave radio communications, which were being used by amateurs and professionals in emergency response efforts, although it does not detail how emergency efforts may have been affected by the radio blackout.

“Safeguards put in place to prevent dangerous disruption to GPS from solar events worked,” said Mike Hapgood, head of space weather at Rutherford Appleton Laboratory in the United Kingdom, and a scientist not connected to the new study. “In many ways, we were ready. Some things that could have caused big problems didn’t, but shortwave radio is always tricky to use during solar events. But good radio operators are aware of the events and will work hard to overcome problems.”

“It’s the Sun reminding us that it’s there,” Hapgood added. “The Sun’s been very quiet for the last 10 years. It reminds people not to be complacent.”

Unexpected space weather

The 2017 flares were the largest since 2005 and the best documented solar storm to date, observed from a fleet of spacecraft between the Earth and the Sun, in Earth’s orbit, on Earth and Mars.

Solar flares release bursts of X-rays from the Sun that travel outwards in all directions at the speed of light. Strong flares can disrupt radio and aviation communications. Space weather forecasters have only minutes to broadcast warnings to spacecraft, aviation and other administrators before affects are felt on Earth.

X-rays from solar flares interact with Earth’s atmosphere 50-1000 kilometers (30-600 miles) above the Earth, in a region called the ionosphere. Shortwave radio communication works by bouncing signals off the ionosphere and refracting them back to Earth. When the Sun releases a burst of x-rays, like the flares released in early September, the extra energy delivered to the ionosphere can cause it to absorb high frequency radio signals, like those used by ham radio enthusiasts.

— Read more in R. J. Redmon et al., “September 2017’s Geoeffective Space Weather and Impacts to Caribbean Radio Communications during Hurricane Response,” Space Weather (25 July 2018) (DOI: 10.1029/2018SW001897)