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Chemistry change in the stratosphere from the Tonga Volcano

The Hunga Tonga–Hunga Haʻapai undersea volcano eruption on 15th January has injected abnormal levels of moisture into the upper Stratosphere and Mesosphere 30 to 60km above the earth’s surface. It continues to spread across the globe according to NASA’s latest observations. It's also possibly the cause of vivid brighter than normal pre-dawn and post-dusk skies reported across New Zealand in the last few weeks, with diffraction and interference of light waves visible when the sun is around 10 degrees below the horizon. This is a similar effect to what causes the Noctilucent cloud phenomena.

Today's pre-dawn sky showing signs that Tonga’s volcanic eruption has changed the chemistry of the stratosphere

The eruption reached 58km into the atmosphere is likely to be the most explosive natural event on earth since the 1912 Novarupta eruption on the Alaska Peninsula. Latest estimates based on an underwater mapping survey performed by volcanologists are rating the volcanic eruption a level 6 on the VEI scale that goes up to 8. As of the today, low level volcanism continues at the volcano’s caldera.

What does it mean for the atmosphere and the climate? While there are scientific theories, no one knows for sure at this point. An event of this power and size has never been technically observed before due to short term stratospheric moisture records (NASA only since 2004). The 1912 Novarupta eruption on the Alaska Peninsula dropped the earth’s temperature by half a degree from mid-1912 to 1914, likely due to the chemistry change in the stratosphere weakening solar radiation that was bound for earth.

NASA's latest water vapour measurements showing abnormal levels of moisture trapped in the stratosphere.

Stay tuned for more over the coming months as the atmospheric event continues to unfold.

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