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When the Hunga Tonga-Hunga Ha’apai volcano erupted underwater in January, it created a plume of ash and water that passed through the third layer of Earth’s atmosphere.
It was the highest volcanic plume and it reached the mesosphere, where meteors and meteorites usually separate and burn up in our atmosphere.
The mesosphere, about 31 to 50 miles (50 to 80 kilometers) above the Earth’s surface, is above the troposphere and stratosphere and under two other layers. (The stratosphere and mesosphere are dry atmospheric layers.)
The volcanic plume reached an altitude of 35.4 miles (57 kilometers) at its highest. It surpassed previous record holders such as the 1991 Mount Pinatubo eruption in the Philippines at 24.8 miles (40 kilometers) and the 1982 El Chichón eruption in Mexico, which reached 19.2 miles ( 31 kilometers).
The researchers used images captured by satellites passing over the site of the eruption to confirm the height of the plume. The eruption occurred on January 15 in the southern Pacific Ocean off the Tonga archipelago, an area covered by three geostationary weather satellites.
A study detailing the results published Thursday in the journal Science.
The towering plume sent into the upper layers of the atmosphere contained enough water to fill 58,000 Olympic swimming poolsaccording to previous detections from a NASA satellite.
Understanding the height of the plume can help researchers study the impact the eruption could have on global climate.
Determining the height of the plume posed a challenge for researchers. Typically, scientists can measure the altitude of a plume by studying its temperature – the colder a plume, the higher it is, said study co-lead author Dr Simon Proud of RAL Space and researcher at the National Earth Observation Center and at the University. of Oxford.
But this method could not be applied to the Tonga event due to the violent nature of its eruption.
“The eruption passed through the layer of atmosphere we live in, the troposphere, into the upper layers where the atmosphere gets warmer as you go up,” Proud said by email.
“We had to find another approach, using the different views provided by weather satellites on either side of the Pacific and some pattern matching techniques to determine altitude. years, because even ten years ago we didn’t have the satellite technology in space to do that.
The research team relied on the “parallax effect” to determine the height of the plume, comparing the difference in appearance of the plume from multiple angles captured by weather satellites. Satellites took images every 10 minutes, documenting the plume’s dramatic changes as it emerged from the ocean. The images reflected differences in plume position from different lines of sight.
The eruption “went from nothing to a 57 kilometer high tower of ash and cloud in 30 minutes,” Proud said. Team members also noticed rapid changes at the top of the eruptive plume that surprised them.
“After the initial large explosion 57 kilometers away, the central plume dome collapsed inwards, before another plume appeared shortly thereafter,” Proud said. “I didn’t expect something like this to happen.”
The amount of water the volcano has released into the atmosphere is expected to temporarily warm the planet.
“This technique not only allows us to determine the maximum height of the plume, but also the different levels in the atmosphere where volcanic material was released,” said study co-author Dr Andrew Prata, assistant postdoctoral research fellow at the sub-department of Clarendon Laboratory. Atmospheric, Oceanic and Planetary Physics at the University of Oxford, by e-mail.
Knowing the composition and height of the plume can reveal how much ice was sent to the stratosphere and where the ash particles were released.
Height is also critical for aviation safety as volcanic ash can cause jet engine failure, so avoiding ash plumes is essential.
The height of the plume is another detail emerging from what has become one of the most powerful volcanic eruptions on record. When the underwater volcano erupted 65 kilometers north of Tonga’s capital, it triggered a tsunami and shock waves that rippled around the world.
Research is ongoing to find out why the eruption was so powerful, but that may be because it happened underwater.
The heat from the eruption vaporized the water and “created a steam explosion much more powerful than a volcanic eruption normally would be,” Proud said.
“Examples like the Hunga Tonga-Hunga Ha’apai eruption demonstrate that magma-seawater interactions play an important role in producing highly explosive eruptions that can inject volcanic materials at extreme altitudes,” Prata added. .
Next, the researchers want to understand why the plume was so high as well as its composition and its continued impact on the global climate.
“A lot of times when people think of volcanic plumes, they think of volcanic ash,” Prata said. “However, preliminary work on this case reveals that there was a significant proportion of ice in the plume. We also know that there was a fairly modest amount of sulfur dioxide and sulphate aerosols formed soon after the plume. ‘eruption.
Proud wants to use the multi-satellite altitude technique in this study to create automatic warnings for severe storms and volcanic eruptions.