Radio blackouts caused by intense solar storms complicated 2017 hurricane relief efforts
According to a newly published paper, powerful solar storms were responsible for communication outages in 2017, as professionals and volunteers alike worked to provide emergency aid in the wake of the devastation caused by hurricanes Irma, Katia and Jose. The source of the interference was a series of enormous solar flares, which were responsible for disrupting Earth's atmosphere and preventing radio signals from reaching their targets.
From the perspective of Earth, the Sun (when viewed through a telescope or camera with the correct solar filter) often looks relatively placid, albeit marked by transient dark regions known as sun spots. Astronomers tasked with observing the powerhouse of our solar system understand that this is about as far from the truth as it is possible to get. The Sun is phenomenally active, and often gives rise to explosively energetic events known as solar flares, and coronal mass ejections (CMEs).
Both of these spectacular events are driven by the magnetic field of our star, and both are responsible for hurling vast quantities of radiation and fast-moving, high-energy particles into space. The difference is that CMEs are much larger and more powerful than solar flares, with the most colossal of the events capable of containing billions of tons of matter, which can be accelerated away from the Sun at a rate of several million miles per hour.
The material cast out during a solar storm continues through interplanetary space, unless that is, it happens to collide with one of the planets inhabiting our solar system. Solar flares and CMEs can occur together, or independently of one another.
In recent years the Sun has been relatively quiet, but that changed in September 2017. Our star then gave birth to three massive solar storms that reached Earth just as humanitarian efforts attempted to mitigate the destruction caused by the terrestrial storms, Irma, Katia and Jose.
The 2017 flares were the most intense since 2005. The first two solar flares occurred on the morning of September 6, 2017, and were accompanied by powerful CME events. A third flare erupted from our star on September 10.
By the time the particles and radiation thrown out by the storms reached Earth, the trio of hurricanes had brought major devastation to entire countries, leading to numerous humanitarian crises. Hurricane Irma alone was responsible for destroying 95 percent of the buildings on the small island of Barbuda, and causing widespread damage to the Bahamas, the US, and the British Virgin Islands.
In the wake of the destruction, emergency services and volunteers relied in part on short wave radio transmissions to help coordinate relief efforts, disseminate information, and let the loved ones of those in the path of the hurricanes know that they were safe. Unfortunately, radio transmissions are very susceptible to disruption stemming from extreme space weather events.
Shortwave radio equipment works by bouncing signals off a part of Earth's atmosphere known as the ionosphere – a region roughly 50 to 1,000 km (30 to 600 miles) above our planet's surface that is particularly sensitive to the after effects of a solar storm.
X-rays emitted by solar flares and CMEs can strike the ionosphere at incredible speeds, and the extra energy imparted during this interaction can cause Earth's atmosphere to absorb a radio signal instead of bouncing it back to Earth.
"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," comments Bobby Graves, an experienced ham radio operator who manages the Hurricane Watch Net – a group of trained and licenced amateurs tasked with providing communications support during storm emergencies. "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."
A newly published study, which is itself an overview of a number of separate papers that covered the solar activity and subsequent issues that occurred in September 2017, has detailed the extent of the disruption to relief efforts caused by the solar activity.
According to the authors, the space weather led to a loss of radio communication for most of the early morning, going on through to the early afternoon of September 6, which also resulted in a blackout of communications with a French cargo plane that lasted for a full 90 minutes. High frequency radio systems used by airplanes, maritime, emergency bands were inoperable for roughly eight hours.
The large solar flare that occurred on September 10 caused a further three-hour blackout period for radio communications, which took place during a critical period in the wake of hurricanes Jose and Irma's assault on several islands, including the Bahamas and Cuba.
The 2017 solar storms were the most closely observed flare and CME events to date, and were analyzed by a number of Earthbound telescopes, as well as a fleet of spacecraft located in Earth's orbit, and beyond. The authors of the papers that comprise the new collection hope that their findings will lead to improvements in how solar storms are predicted, and how we can better guard against them.
Scroll down to watch a NASA video showing the September 10 solar flare erupt from the surface of the Sun.
The study has been published in the journal Space Weather.
Source: The American Geophysical Union