With the research plane through the volcanic cloud

Unique measuring system delivers rare climate data

View on the southeast side of the Kasatochi after the eruption of 7.8.08. The cliff in the flank marks the former coastline. The formerly green island is covered by dust and ash. The same dust that Caribic scientists have measured in the air over Europe. © Chris Waythomas / ASV / USGS
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With a unique measuring system aboard a passenger plane, researchers have flown through the plume of a volcanic eruption, collecting rare climate data. As the scientists report in the journal "Geophysical Research Letters", the results could help to better estimate the effect of volcanoes on the atmosphere and the climate.

They show that the eruption of the Kasatochi volcano in the Pacific had increased the sulfur concentration in the samples by a factor of 10, and the number of finest dust particles by a factor of 1, 000. In addition to potentially climate-cooling sulfur, the measured particles contained unexpectedly high levels of potentially warming carbon. The monthly measurement flights within the CARIBIC project showed three times more sulfur concentration than in normal parts of the northern hemisphere even four months later.

Kasatochi hurls 1.5 million tons of sulfur dioxide into the air

After 200 years of calm, the volcano Kasatochi, which lies between Kamchatka and Alaska in the Pacific, exploded on August 7, 2008. In a huge cloud of gas and ash, he threw about 1.5 million tons of sulfur dioxide so high in the air that they reached the stratosphere - the layer of air above the atmospheric layer of the atmosphere. This means that the particles are washed out of this layer more slowly because no precipitate forms there.

Enormously high sulfur values

The stream of air, known as the jet stream, transported the plume of the volcano to Europe. There, the specially adapted Lufthansa Airbus "Leverkusen" flew through the cloud in the hold with the flying atmosphere laboratory CARIBIC of the Max Planck Institute for Chemistry in Mainz (MPIC) in the cargo hold, surveying and sampling it.

In the cloud, on the way from Alaska to Europe, part of the gaseous sulfur dioxide was transformed into tiny liquid sulfuric acid droplets and sulfates. The scientists were drawn to their rare find, as the sulfur analyzes of the aerosol samples, carried out at the University of Lund, had extremely high values. display

Measuring exhaust gas of the Kasatochi

"Our colleagues from the Institute for Tropospheric Research in Leipzig then took a closer look at the number and size of particles in the samples, " says project coordinator Professor Carl Brenninkmeijer from the MPIC. We here in Mainz have analyzed in more detail the sulfur dioxide content via the spectral analyzes of the scattered sunlight. And together it was clear: We measured the exhaust plume of the Kasatochi

A rare event: "We have data from almost ten years now, but this is the first clear, detailed signal of a volcanic eruption that we were able to measure, " says Brenninkmeijer. There are few natural experiments of this kind for us atmospheric researchers. We are very interested in violent volcanic eruptions, as the vast amounts of ash and gases affect many processes and ultimately the climate. "

It is known that sulfur in the form of sulfur droplets cools the climate. As early as 1961, Christian Junge discovered the boy layer named after him. It consists of sulfur tufts and spans the earth 20 to 30 kilometers above the ozone layer.

Artificial volcanic eruptions?

The droplets reflect and scatter the sunlight, so that less energy arrives on the earth - it remains a little cooler, says Brenninkmeijer. Nobel laureate Paul Crutzen suggested that it might be possible to deploy a sulfuric acid climate emergency brake into the stratosphere. An experiment that he wishes for himself, that it never has to be done. Since the young layer is partly fed by violent volcanic eruptions, this emergency measure would be roughly comparable to artificial volcanic eruptions.

Interestingly enough, we also found large amounts of carbon in the ash particles of the kasatochi. In contrast to the pure sulfur particles, these darkly colored particles can absorb heat, so that they counteract the sulfur effect, "explains Brenninkmeijer.

Soon new results?

Whether the ashes of the Kasatochi are unusual in this regard, the researchers can not say right now, as they have no comparative measurements. "But we are working hard and hope to be able to submit further results later this year, " said Brenninkmeijer.

(idw - Max Planck Institute for Chemistry, 06.07.2009 - DLO)