A new study examines the 2014 eruption of Mount Kelut (or Kelud) on the Indonesian island of Java. On
The study began with random observation: members of the research team flew an unmanned aircraft near the site of the eruption of the Kelut volcano, an event that covered much of Java in ash and forced people to flee their homes. At the same time, passengers noticed something that should not be there.
A month after the eruption, the atmosphere is stillthere were large particles, ”said Yunqian Zhu, lead author of the new study and researcher at the Laboratory of Atmospheric and Space Physics (LASP) at CU Boulder. "It looked like ash."
She explained that scientists have long known thatvolcanic eruptions can affect the planet's climate. These events lead to the release of huge amounts of sulfur-rich particles high into the Earth's atmosphere, where they can block sunlight from reaching the earth.
However, the researchers did not think that ash couldplay a big role in this cooling effect. Scientists have concluded that these chunks of rock debris are so heavy that most of them probably fell out of volcanic clouds shortly after the eruption.
Zhu's team wanted to find out why it wasn't.happened in the case of the eruption of Kelut. Based on aircraft data and satellite observations of the unfolding disaster, the team found that the volcano's plume appears to be teeming with small, light ash particles - tiny particles that could probably float in the air for extended periods of time, like dandelion fluff.
Study co-author Brian Thun added that these pumice-like particles also change the chemistry of the entire volcanic plume.
Thun, professor at LASP and the Department of Atmospheric andOcean Sciences at CU Boulder, explained that erupting volcanoes emit large amounts of sulfur dioxide. Many researchers have previously suggested that these molecules interact with others in the air and turn into sulfuric acid - a series of chemical reactions that could theoretically take weeks to complete. However, observations of real eruptions show that this happens much faster.
A NASA Global Hawk unmanned aircraft that observed the ash left in the air after the eruption. Credit: NASA / Dryden / Carla Thomas.
A mystery has arisen as to why these reactions occurso fast. However, scientists have found the answer: These sulfur dioxide molecules seem to stick to ash particles floating in the air. In the process, they can enter into chemical reactions on the surface of the ash itself, potentially pulling about 43% of the sulfur dioxide out of the air.
In other words, ash can accelerate the transformation of volcanic gases in the atmosphere.
It is unclear how these ash clouds affect the climate. In theory, long-term particles in the atmosphere can darken the planet and even contribute to its cooling after an eruption. Floating ash can also be carried away from places like Keluth to the poles of the planet. There, it can trigger chemical reactions that will damage the Earth's most important ozone layer.
But the researchers say one thing is clear: when the volcano erupts, it may be time to pay much more attention to ash and its true impact on Earth's climate.
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