Volcanic Plume Over Southern Atlantic Ocean Revealed Through False-Colour Imagery

Image Credit: Jeff Schmaltz /MODIS Land Rapid Response Team, NASA GSFC

The South Sandwich Islands, in the far southern Atlantic Ocean, are often shrouded with thick cloud, making it difficult to view the region from space.

Sometimes, however, the use of false-colour imagery can be used to reveal events that would otherwise be obscured under cloud cover.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite flew over the South Sandwich Islands on April 19, 2014 and acquired this false-colour image of the cloudy scene.

This false-colour image uses a combination of non-visible (middle infrared and infrared) and visible (red) light captured in bands 7, 2, and 1, respectively, to distinguish clouds from snow and ice.

Here the ice-covered islands appear bright turquoise, the clouds light turquoise and the water in the ocean appears deep black.

Because the volcanic plume is a moist mixture of gas and ash, it reflects all three forms of light relatively well, so it appears nearly white.

In the north of this image, a thin plume of white rises from the volcano on Zavodovski island, the northernmost of the South Sandwich Islands and streams to the northeast.

Further south, a wider white plume can be seen blowing across the Atlantic Ocean.

This plume rises from the Mount Michael volcano, which is a young and frequently active stratovolcano located on Saunders Island, near the center of the South Sandwich Island chain.

The white plume from Mount Michael forms a chain of swirling eddies as it blows to the northeast.

To the south, similar eddies can be seen behind three other islands. These are known as Von Kármán vortices.

These vortices can form nearly anywhere that fluid flow is disturbed by an object. Because the atmosphere behaves like a fluid, when streaming air hits a blunt object, such as a mountain peak, the wind is forced around the object.

The disturbance in the flow of the wind propagates downstream in a double row of vortices that alternate their direction of rotation, much like the eddies seen behind a pier in a river as water rushes past.

NASA Flies Dragon Eye Unmanned Aircraft Into Turrialba Volcanic Plume

The study launched 10 flights between March 11-14, 2013, into the volcanic plume and along the rim of the Turrialba summit crater approx. 10,500 feet above sea level. 

Image credit: NASA/ Matthew Fladeland.

NASA Earth science researchers last month traveled to Turrialba Volcano, near San Jose, Costa Rica, to fly a Dragon Eye unmanned aerial vehicle (UAV) -- a small electric aircraft equipped with cameras and sensors -- into the volcano's sulfur dioxide plume and over its summit crater, to study Turrialba's chemical environment.

The project is designed to improve the remote-sensing capability of satellites and computer models of volcanic activity.

The study, called "In Situ Validation and Calibration of Remotely Sensed Volcanic Emission Data and Models," launched 10 flights between March 11-14, 2013, into the volcanic plume and along the rim of the Turrialba summit crater approximately 10,500 feet above sea level (ASL).

The launch site was located at 8,900 feet ASL, and flights ranged up to 12,500 feet ASL, more than 2,000 feet above the Turrialba summit. Project objectives included improving satellite data research products, such as maps of concentration and distribution of volcanic gases, and transport-pathway models of volcanic plumes.

During the research flights, the team coordinated its data gathering with the Advanced Spaceborne Thermal Emission and Reflection (ASTER) instrument on NASA's Terra spacecraft, allowing scientists to compare sulfur dioxide concentration measurements from the satellite with measurements taken from within the plume.

Scientists believe computer models derived from this study will contribute to safeguarding the National and International Airspace System, improve global climate predictions, and mitigate environmental hazards (e.g., sulfur dioxide volcanic smog or "vog") for people who live around volcanoes.

A key factor of such models is the intensity and character of the volcanic activity located near the eruption vent. For instance, knowing the height of ash and gas concentrations, and temperatures over the vent during an eruption are important initial factors for any model that predicts the direction of the volcanic plume.

"It is very difficult to gather data from within volcanic eruption columns and plumes because updraft wind speeds are very high and high ash concentrations can quickly destroy aircraft engines," said David Pieri, the project's principal investigator and a research scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.

"Such flight environments can be very dangerous to manned aircraft. Volcanic eruption plumes may stretch for miles from a summit vent, and detached ash clouds can drift hundreds to thousands of miles from an eruption site.

To penetrate such dangerous airspace, UAVs, especially those with electric engines that ingest little contaminated air, are an emerging and effective way to gather crucial data about ash and gas concentrations and their lateral and vertical distribution.

To accomplish project objectives, research scientists at NASA's Ames Research Center, Moffett Field, Calif., used three Aerovironment RQ-14 Dragon Eye UAVs which were acquired from the United States Marine Corps (USMC) via the General Services Administration's San Francisco office. These small electric unmanned aircraft weigh 5.9 pounds, have a 3.75-foot wingspan and twin electric engines, and can carry a one-pound instrument payload for up to an hour within a volcanic plume.

"This project is great example of how unmanned aircraft can be used for beneficial civilian purposes - in this case for better understanding Earth system processes and the impact of volcanism on our atmosphere," said Matthew Fladeland, airborne science manager at Ames. "By taking these retired military tools, we can very efficiently and effectively collect measurements that improve NASA satellite data and aviation safety."

Jupiter's Moon Io Video: Volcanic plume

NASA's New Horizon mission snapped imagery of volcanic debris emanating from Io's Tvashtar volcano in 2007. The plume reaches up to 205 miles above the surface of Io.

Credit: NASA /Johns Hopkins University Applied Physics Laboratory /Southwest Research Institute