OMI Measures Volcanic Gas Cloud

On May 20, 2006 a major lava dome collapse at the Soufriere Hills volcano on Montserrat (West Indies) triggered an explosive emission of volcanic gases. The resulting gas cloud penetrated the stratosphere, reaching an altitude of ~20 km. Sulfur dioxide (SO₂) in this cloud was tracked by OMI for 3 weeks as it moved westwards across the Pacific, before finally dissipating below detection limits over the Indian Ocean on June 11.

The CALIPSO lidar saw the volcanic sulfate aerosol plume on the orbit pass shown below. SO₂ is a gas, but it slowly turns to sulfuric acid droplets as SO₂ reacts with OH in the stratosphere. The CALIPSO aerosol lidar spotted the small cloud of droplets forming in side the SO₂ plume that OMI sees. CALIPSO is orbiting a few minutes ahead of Aura.

CALIPSO "First Light" Images : June 2006
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* Note that the SO₂ scale used is normalized to the maximum SO₂ column measured on each day (Normalized SO₂ column = [SO₂ column/Max SO₂ column]*100).