The phenomenon baffles researchers
The eruption of the Tonga volcano last Saturday, which caused a tsunami alert on both sides of the Pacific and the disappearance of the island, sent massive waves never seen before in the Earth’s atmosphere. The phenomenon has puzzled scientists, who had never observed such a signal after a volcanic eruption.
“It’s really unique. We’ve never seen anything like this in the data before,” says Lars Hoffmann, an atmospheric scientist at the Jülich Supercomputing Center in Germany, in ‘Nature’. The waves were discovered in images from the Atmospheric Infrared Sounder (AIRS), aboard NASA’s Aqua satellite, in the hours after the eruption. The photos show dozens of concentric circles, each representing a fast-moving wave of gases in the atmosphere, stretching for more than 10,000 miles.
The waves reached from the ocean surface to the ionosphere, and the researchers believe they probably circled the globe multiple times. “This instrument has been running for about 20 years and we have never seen such beautiful concentric wave patterns,” Hoffmann tells the publication.
Gravity waves in the atmosphere are produced when air molecules are disturbed vertically, rather than horizontally, in the air column. This can happen when the wind picks up speed as it rises over a mountain top or during a storm.
Theoretically, they can also be caused by the eruption of a volcano, but the truth is that nothing similar has been observed in other eruptions studied with the AIRS instrument since its launch in May 2002.
The researchers do not explain why it happened this time. Corwin Wright, an atmospheric physicist at the University of Bath, UK, points out in ‘Nature’ that it may be due to a “large, messy pile of hot gases”. The hot gas is “rising high into the stratosphere and hitting the air.” For his part, Scott Osprey, a climate scientist at the University of Oxford, UK, believes that the mysterious waves have to do with the speed at which the event occurred, which was explosive.
In addition, the volcano increased atmospheric pressure throughout the world, a change that was also perceived by different barometers in Spain.
