The eruption of the Hong Tonga volcano, which sent shock waves across the Earth in January 2022, led to the formation of the highest volcanic cloud since at least the 1883 eruption of Krakatoa, a new study reports. The amount of water the volcano injected into Earth’s atmosphere may have warmed the planet’s climate.
The volcanic eruption that tore the island of Polynesia Tonga-Henga Sabai January 15th was a domestic disaster, but it also proved to be a scientific gift that keeps on giving. A once-modest underwater volcano in a remote part of the South Pacific has exploded with unprecedented force in full view of three weather satellites. These satellites It allowed scientists around the world to observe the amazing explosion in real time and study its effects in unprecedented detail.
Among the researchers who were caught by mushrooms of water vapor and metallic ash that shot up into the sky that fateful evening was Simon Proud, an Earth observation scientist at STFC Rutherford Appleton Laboratory and Oxford University in the UK.
Related: A massive volcanic eruption in Tonga has sent record-breaking winds to the edge of space
Proud, lead author of a new study analyzing the plume, soon realized that the Hong Tonga eruption was completely out of the ordinary. For example, temperature measurements returned by Earth observation satellites suggested that the volcanic cloud must have reached an unprecedented height.
“When [the cloud] It was developing, we were looking at temperatures based on satellite data,” Proud told Space.com. It passed through the troposphere, where the temperature decreases with altitude, and then continues to cool even though the atmosphere around it should have gotten warmer.”
Scientists usually estimate the height of atmospheric phenomena by measuring their temperature using satellite-borne infrared sensors and comparing these measurements to the temperature of the surrounding atmosphere. In the troposphere, layer Earth’s atmosphere Closer to the surface of the planet, the temperature decreases with altitude according to the known rules of physics. But those rules no longer apply in the stratosphere, the layer of the atmosphere that extends from 9 miles to 30 miles (15 to 50 kilometers) in altitude, where the ozone layer absorbs ultraviolet radiation from the sun, which leads to higher temperatures. As the Hunga Tonga cloud continues to cool down, Proud realized that accurately estimating the altitude required a more creative approach.
Since three different weather satellites observed the eruption from three different locations in the geostationary orbit, an orbit about 22,000 miles (36,000 km) high where objects appear to hang over a fixed spot on Earth, Proud was able to calculate the height of the top of the cloud using method known as the view.
Parallax allows researchers to calculate the distance to an object using the apparent distances as observed from at least two different locations. Usually used to calculate distances starsand the Proud you previously used to calculate the height Chelyabinsk meteorite that exploded over Russia in 2013.
“We were really lucky to have the area covered by three satellites,” Proud said. “[The calculation] It yielded really good results; It worked very well for such a high volcano. We’ve never seen everything this high before.”
Calculations revealed that the Hunga Tonga cloud not only erupted through the troposphere, but also ascended through the entire stratosphere, plateauing only 35 miles (57 km), reaching the frozen, dry layer known as the mesosphere. This makes the Hongja Tonga volcanic cloud the highest ever observed and probably the highest in over a century.
“the last [volcanic eruption] He proudly said, “It could have been as high as Krakatoa in 1883.” There were some more recent [eruptions] Such as [the 1991 eruption of] Mount Pinatubo, and we think we underestimated the height of those, but not to the same degree.”
Ash has been detected from the eruption of Mount Pinatubo in Elevations of up to 25 miles (40 km (Opens in a new tab)). Proud believes that if the better satellites were in orbit at the time, the cloud’s traces would have been seen 6 miles (10 km) high, but still less than 35 miles away in Hong Tonga.
Pinatubo’s ashes in the stratosphere Earth’s climate cooled by 1 degree Fahrenheit (Opens in a new tab) (0.6 °C) due to the presence of sulfur dioxide in the volcanic material. Sulfur dioxide reflects radiation and is frequently studied as part of the potential geoengineering Interventions designed to slow down Climate change.
When the Hang Tonga erupted, scientists believed that a volcanic eruption could produce a similar effect (which, in the case of Pinatubo, was observable for two years). However, subsequent measurements revealed that The Hongga Tonga cloud contained only about 2% of sulfur dioxide Created by Pinatubo, it is not enough to affect the climate in any measurable way. However, Proud says that the amount of water the explosion sprayed into the stratosphere may actually be warming the climate.
“This volcano put a lot of water into the stratosphere and some of it also into the mesosphere,” Proud said. “Water in the stratosphere is generally heating up the Earth’s surface. So this can actually contribute to the rise in ground level sometimes over the next few years. We have very good temperature data for the lower atmosphere, so this is something we have to be able to I get to figure it out quite quickly.”
A study published earlier this year found that Hunga Tonga injected the equivalent of 58000 Olympic-sized swimming pools in Earth’s atmospherewhich increases the amount of water vapor in the stratosphere by 5%.
Proud said the effects on the mesosphere may be more subtle and come with some interesting side effects.
“The atmosphere is usually the driest layer in the atmosphere, and putting more water in there could mean we’re getting more polar clouds in the atmosphere,” Proud said. “These clouds are getting more common anyway, probably because of climate change, so I want to look at the satellite data and see if I can see an increase after this eruption.”
Polar atmospheric clouds, also known as night clouds For its ability to glow at night, it forms during the summer months over the polar regions at altitudes from 47 miles to 53 miles (76 to 85 km). Often these clouds appeared in the wake space shuttle launchwhich emits huge amounts of water vapor in the exhaust of its missiles.
Proud said the mesosphere is a bit unexplored because it’s too low for satellites to fly through but too high for balloons to reach. Therefore, the eruption of Hongja Tonga may represent a unique incentive for scientists to look at the chemical processes unfolding in this region.
Researchers are by no means finished with the eruption of the Hong Tonga volcano. Many questions remain unanswered, including its exact effect on Earth’s climate and why it exploded with such force after centuries of lukewarm activity.
The new study (Opens in a new tab) It was published online in Science Today (November 3).
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