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With technology becoming more integrated into our daily lives, it is increasingly important to understand space weather and its impacts on technology.
When you hear “space weather,” you usually think of huge explosions on the Sun: coronal mass ejections hurled toward Earth, creating beautiful auroras.
However, not all space weather starts on the Sun.
The volcanic eruption in Tonga in January 2022 was so large that it created ripples in the upper atmosphere that constituted its own form of space weather.
It was one of the largest explosions in modern history, affecting GPS in Australia and Southeast Asia. As we describe in our new study in the journal space weatherthe eruption caused a super “plasma bubble” over northern Australia that lasted for hours.
A true global positioning system
While most people have a GPS (global positioning system) receiver on their devices (such as sat navs and smartphones), not many know how GPS actually works.
In essence, our devices listen to radio signals transmitted by satellites orbiting the Earth. Using those signals, they calculate your location in relation to satellites, allowing us to orient ourselves and find that nearby pub or cafe.
The radio signals our devices receive are affected by Earth’s atmosphere (particularly the layer called the ionosphere), which degrades location accuracy. Common devices are only accurate to tens of meters.
However, new and improved precise satellite positioning systems, used in the mining, agricultural, and construction industries, can be accurate to within four inches. The only drawback is that these systems need time to lock on your location, and this can take thirty minutes or more.
This precise satellite positioning works by accurately modeling errors caused by Earth’s ionosphere. But every time the ionosphere is disturbed, it becomes complicated and difficult to model.
For example, when a geomagnetic storm (a disturbance in the solar wind impacting the Earth’s magnetic field) occurs, the ionosphere becomes turbulent, and radio waves traveling through it are scattered, like visible light. that deviates and scatters when looking down. lake in choppy conditions.
a volcanic disruption
Recent studies have shown that the eruption of the Hunga Tonga-Hunga Ha’apai volcano caused choppy conditions in the ionosphere that lasted for a few days. The size of the waves it generated in the ionosphere were similar in size to those created by geomagnetic storms.
While these waves influenced GPS data around the world for days after the eruption, their impact on positioning was fairly limited compared to another type of disturbance in the ionosphere: a “super plasma bubble” that formed following the eruption.
The ionosphere is a layer of Earth’s atmosphere at altitudes of about 80 to 800 kilometers (50 to 500 miles). It is made up of gas with many electrically charged particles, making it a “plasma”.
In turn, equatorial plasma bubbles are disturbances of plasma in the ionosphere that occur naturally at night over low latitude regions.
Such plasma bubbles occur regularly. They form due to a phenomenon called “generalized Rayleigh-Taylor instability.” It’s similar to what happens when a heavy fluid sits on top of a lighter fluid, and droplets of this lighter fluid rise toward the heavy fluid in the form of “bubbles” (see video below).
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However, when it comes to disturbances in the ionosphere, the plasma is also controlled by magnetic and electric fields.
As they rise, the plasma bubbles form strangely shaped structures resembling cacti or upside-down tree roots. Due to Earth’s magnetic field, these structures fan out as the bubble grows above the equator.
The result is that higher altitude bubbles also reach higher latitudes. Plasma bubbles typically reach a few hundred kilometers above the equator, reaching latitudes between 15 and 20 degrees north and south.
A rare bubble over Australia
Scientists detected a super bubble of plasma over Southeast Asia shortly after the Tonga eruption. It is estimated to be similar in size to previously reported rare super bubbles.
Earth’s magnetic field carried this disturbance south, where it lingered for a few hours over Townsville in northeast Australia.
To date, this is the southernmost plasma bubble that has been observed over Australia. While very rare, these super bubbles are known to have taken place in northern Australia, but they had not been directly observed prior to this event.
The deployment of GPS stations in northern Australia has recently made this type of observation possible.
Waves from the volcano’s eruption are understood to have disturbed winds in the upper atmosphere, altering the flow of plasma in the ionosphere and giving rise to the super plasma bubble.
Our study found that the bubble caused significant delays in the use of accurate GPS in Northern Australia and Southeast Asia. In some cases, getting a lock on the GPS location took over five hours due to the plasma bubble.
Although we understand a lot about the ionosphere, our ability to predict its disturbances is still limited. Having more GPS stations is not only beneficial for improving positioning and navigation, but also fills in the gaps in ionospheric monitoring.
The Tonga eruption was far from a typical “space weather” event caused by the Sun. But its impact on the upper atmosphere and GPS highlights the importance of understanding how the environment affects the technologies we rely on.
Brett Carter, Associate Professor, RMIT University; Rezy Pradipta, Senior Research Scientist, Boston College, and Suelynn Choy, Professor
This article is republished from The Conversation under a Creative Commons license. Read the original article.
