NASA balloon campaign studies effects of volcanic eruption

The campaign, in Australia's Northern Territory, is part of an effort to better understand the climate effects of volcanic eruptions.

Indonesia's Mt. Kelud exploded in February 2014, sending a plume of ash particles and sulfate aerosol -- small droplets of sulfuric acid -- up to 15 miles (25 kilometers) high into Earth's stratosphere.

"The purpose is to better characterize particle sizes, composition, and optical properties from a relatively fresh volcanic plume in the stratosphere," said Duncan Fairlie, a scientist at NASA's Langley Research Center in Hampton, Virginia, and the campaign's principal investigator.

The KlAsh (Kelud Ash) experiment is based in Darwin, Australia, where smaller balloon payloads are being launched over the Indian Ocean. Larger balloons, with payloads that must be recovered, are being launched from Corroboree, a remote area about 60 miles south of Darwin. The campaign began May 14 and ends May 28.

"It has gone really well. We have had five successful launches of our small balloons, and launched the big balloon from Corroboree on Tuesday night," Fairlie said. "On all flights we sampled the volcanic plume at around 20 kilometers (about 12 miles) altitude, and have good data to analyze."

The larger balloon, filled with helium, measures about 115 by 65 feet when fully inflated.

"The big balloon launch was a huge undertaking, and recovery of the instrument and balloon the next day involved bushwhacking a mile or so off the road in rough terrain in hot, humid conditions," Fairlie said.

Mt. Kelud was chosen because effects of the eruption are still present in the atmosphere to study, and for its proximity to a suitable staging area.

"A relatively flat and broad land mass is required to launch and recover our sondes (balloon instruments), and we need a land mass that is within 10 to 15 degrees of the equator to measure the plume," said Travis Knepp, one of the team members. "Australia provides the best opportunity to meet these criteria."

Bushwhacking balloons

Researchers are working in rugged terrain in Corroboree.

"There's not much there, a roadside tavern and a few houses. Much of the land is rangeland, mining tracts, some national park, swampland and a couple rivers," Fairlie said. "We have moved the launch site once already when it became clear that the surrounding bush would be too dense to reliably access the payload."

"There are a few natural hazards to avoid -- the salt-water crocodiles -- "salties" -- are particularly active in these parts," he added. "Then there are snakes, spiders, sharks and jellyfish. We've been advised not to swim in the sea, as the jellyfish sting can be deadly, and not to go on the beach at night, as the salties come up onto the coastal beaches."

In addition to support from NASA headquarters, the campaign is supported by two Langley satellite projects, CALIPSO and SAGE.

The SAGE (Stratospheric Aerosol and Gas Experiment) instrument, due to be launched on the International Space Station in 2015, will also measure aerosols in addition to ozone and water vapor, with its greatest sensitivity in the stratosphere, the stable layer of the atmosphere located between about 20 km and 55 km in altitude. The SAGE legacy began with the Stratospheric Aerosol Measurement (SAM) experiment in 1975. Since then five SAGE instruments have flown in space.

The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite launched in 2006 detects clouds and aerosols -- tiny particles suspended in the air -- enabling scientists to better understand how they form, evolve, interact and affect air quality, weather and climate.

"Measurements from CALIPSO indicate the persistence of ash particles in the plume months after the eruption, and a separation in altitude of ash and sulfate aerosol," said Jean-Paul Vernier, science principal investigator for the mission. "Volcanic ash is generally neglected when considering the impact of volcanic aerosols on climate, so the measurements will improve our understanding of the climate effects of volcanic eruptions."

Almost all of the energy entering Earth's climate system comes from the sun. Some of that energy is absorbed by the planet, while the rest is radiated back into space. Ash and sulfate reflect and absorb energy differently, and may also have different chemical impacts on the stratosphere.

"Understanding those characteristics is important for climate models that include periodic volcanic activity," said Terry Deshler, principal investigator for the University of Wyoming's instrumentation.

NASA and the University of Wyoming are partnering in the balloon campaign with the Australian Bureau of Meteorology in Darwin. The University of Wyoming is flying instruments to measure aerosol particle size and determine the fraction of particles that are ash.

The Bureau of Meteorology is providing local support of the release and recovery of the instruments.

The campaign is also being supported through NASA's Rapid Response and Novel Research in Earth Science program, which is designed to rapidly respond to unforeseen or unpredictable events and opportunities. The program is run by the Earth Sciences Division of NASA's Science Mission Directorate.