Volcano Watch — O-CO2, can you see by the dawn’s early light?

This event , which actually occurred a couple of hours before dawn, marked the successful launch of NASA’s first spacecraft dedicated to the study of carbon dioxide (CO₂) in the Earth’s atmosphere.

The centerpiece of the ambitious mission of the Orbiting Carbon Observatory-2, or OCO-2, is essentially the mapping of CO₂ distribution in Earth’s atmosphere on a continuing basis, for at least two years. While the “OCO-2” acronym nicely describes the target of the mission, there was also an OCO-1 launch back in 2009, but things went awry before the spacecraft reached orbit.

To carry out its mission, OCO-2 will orbit Earth at its poles about every hundred minutes or so as a member of a constellation of half-a-dozen satellites, all of which will be moving together as the “A-Train.” Each “car” in this satellite train is equipped with sensors that collect data that complement each other. For example, while OCO-2 collects CO₂ data, two other satellites, CALIPSO and CloudSat, will be collecting information about clouds and aerosol in the atmosphere at the same time, helping to improve the quality of OCO-2’s findings.

Although measuring CO₂ in Earth’s atmosphere from space does require some rocket science to accomplish, it isn’t the simple detection of CO₂ that’s so difficult, since there’s lots of it in the atmosphere to measure. What makes OCO-2’s job so challenging is that this mission’s chief goal is to help us better understand Earth’s carbon cycle—a global-scale topic with many variables.

In general, human activity and some processes of nature act as CO₂ sources, pumping huge amounts of this greenhouse gas into the atmosphere, while other processes occurring in the oceans and on land act as sinks, removing it. Studies have shown convincingly that before the industrial age, human sources of CO₂ were small, compared with the carbon-removing influence of vegetation, oceans, and other natural processes. Modern carbon inventories indicate that the balance has been tipped the other way: we’re putting more CO₂ into the air than Earth processes can practically remove.

OCO-2 will attempt to unravel this mystery through its mapping of the amount and location of CO₂ in Earth’s atmosphere at an unprecedented level of precision and sensitivity. This feat, if accomplished, will produce a better quantitative understanding of regional CO₂ sources and sinks. To do this, OCO-2 will be using a sophisticated infrared spectrometer system that measures sunlight energy passing through the atmosphere. The sunlight is absorbed in proportion to the amount of CO₂ in the light’s path as it reaches the surface and is reflected back up to the satellite. At the same time, OCO-2 will measure light energy emitted during photosynthetic processes associated with CO₂ removal.

The potential to identify CO₂ sources and sinks is of great interest to volcanologists, as well. Volcanoes can release significant amounts of CO₂ during large eruptions, even though, averaged over time, they add little CO₂ to Earth’s atmosphere on a global scale (less than 0.5 % of that contributed by human activity on average, including large eruptions). Furthermore, volcanic CO₂ is associated with magma supply, so the possibility of measuring CO₂ from space everywhere on the planet, twice a month, could be very helpful for detecting volcanic restlessness at remote volcanic settings worldwide.

Even if the OCO-2 mission is wildly successful, challenges will remain for applying these CO₂ maps to volcanoes. Although the OCO-2 should, theoretically, be able to see fairly small CO₂ concentration differences on the Earth’s surface, the detection footprint (as small as 1 square mile or 3 square km) is of the same order as the central crater of many volcanoes where CO₂ is emitted. And once volcanic CO₂ is released to the atmosphere, it begins to disperse and dilute, making it harder to detect.

A successful OCO-2 mission, one that helps us better understand the quantitative balance between CO₂ sources and sinks on regional and global scales, could help guide efforts to effectively decrease human-made CO₂ emissions. The volcano science community is looking forward to fruits of this mission, as well.

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Volcano Activity Update

A lava lake within Halema‘uma‘u produced nighttime glow that was visible via HVO’s Webcam during the past week. The lava lake level dropped during the week, and was 40–45 m (~130–150 ft) below the rim of the Overlook crater on Thursday, July 10.

On Kīlauea’s East Rift Zone, the June 27 breakout continues to build a low shield, topped by a lava pond on the northeast flank of Pu‘u ‘Ō‘ō. Overflows from the pond, and breakouts from the base of the levee around the pond, fed small flows that rarely reached the base of Pu‘u ‘Ō‘ō.

There were no earthquakes in the past week reported felt on the Island of Hawai‘i.