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Up, Up, and Away: Research Balloons Take to Antarctica's Skies

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A Google Earth image of Antarctica. The red dots indicate locations of research balloon releases over and around Antarctica during the Concordiasi project; the green dots show radio probe locations. (Image credit: Terry Hock, Earth Observing Laboratory, National Center for Atmospheric Research)

This Behind the Scenes article was provided to LiveScience in partnership with the National Science Foundation.

Like salt in soup, research tools often go relatively unnoticed unless missing. Lacking the right tools may result in less-impactful scientific outcomes that are potentially more difficult to achieve. When tools work well, greater possibility exists for discovery, and in some cases the right tool may offer new or unexpected results.

Schematic of the balloon-based driftsonde concept. The driftsonde releases mini-probes which take wind, temperature, humidity and pressure readings, providing critical information used in near-real-time weather forecasting. (Image credit: Terry Hock, Earth Observing Laboratory, National Center for Atmospheric Research)

When the recent Concordiasi Project launched from the McMurdo research station in Antarctica, driftsonde — large, balloon-based probes — technology provided the equivalent of not just the salt for the soup, but the vegetables, protein and broth for the Météo-France and National Science Foundation-funded field campaign.

Drifting research stations

The driftsonde system was developed by a team of mechanical, electrical and software engineers in the National Science Foundation-supported National Center for Atmospheric Research's Earth Observing Laboratory to provide a low-cost way of taking instant measurements through a column of the atmosphere. It looks something like a giant weather balloon — with oversized observing capabilities. Launched from the ground and able to stay aloft for up to several months, driftsonde systems provide Concordiasi researchers with a sophisticated suite of tools.

Fitted with sensors, called dropsondes, which drop from the craft, the driftsondes collect detailed atmospheric information including atmospheric characteristics such as wind, temperature, humidity and pressure.

Operated remotely using a web-based interface, the system's design allows researchers to monitor and control dropsondes via internet from anywhere in the world. This proved helpful because the Concordiasi Project could run 24 hours a day and 7 days a week as operators in Boulder, Colo., and France would transition duties at each day's beginning and end.

Such a continuously connected capability also allowed dropsonde release to occur at desired points along the driftsonde flight path, such as remote geographic areas and during significant weather events.

Incoming dropsonde

As a main focus for Concordiasi, the Earth Observing Laboratory (EOL) team worked closely with Météo-France to ensure that some dropsonde releases coincided with satellite overpasses, allowing validation of the remotely sensed data.

"We also kept an eye on areas that atmospheric models indicated were sensitive to new data, so if something particularly interesting was taking place or about to happen, atmospherically, a dropsonde could be launched," said Steve Cohn, manager of EOL's In-situ Sensing Facility. "The team worked closely with Antarctic modelers and forecasters to identify such events."

On left: An illustration of the research balloon showing the various components. On right: A photo taken during pre-flight testing. (Image credit: Terry Hock, Earth Observing Laboratory, National Center for Atmospheric Research)

The Concordiasi driftsondes were built and deployed by the National Center for Atmospheric Research and flown on super-pressure balloons operated by the French Centre National d'Etudes Spaciales. The project was part of an International Polar Year research effort, with launches occurring in September and October of 2010, some of the driftsondes remained aloft into December.

International project

Météo-France initiated and led the Concordiasi project, which is a combination of "Concordia" for France's Concordia research station located on the Antarctic Plateau and the "iasi" for the Infrared Atmospheric Sounding Interferometer satellite instrument. The interferometer is a key element of the MetOp series of European meteorological polar-orbiting satellites.

One example of how the project helped validate satellite-gathered information is the analysis of radiance data. Polar-orbiting satellites over Antarctica collect information on radiance — snapshots of radiation coming from the Earth's surface or lower atmosphere that can be translated into temperature data, providing insights on surface-level and atmospheric processes. However, satellite-sensor precision varies, which can affect output from weather and climate models using the resulting temperature data. Data validation is imperative, so dropsonde measurements of temperature will help achieve that end.

Equally important to Concordiasi scientists is an effort to better understand stratospheric clouds and related small-scale physical processes. At the best of times, learning about cloud formation and dispersal and the atmospheric characteristics affecting cloud dynamics are nuanced, but at high altitude and in one of the planet's most remote areas, necessary data collection becomes even more of an issue.

Data collection

The flight train of the Concordiasi balloon just after its launch in Antarctica. (Image credit: Terry Hock, Earth Observing Laboratory, National Center for Atmospheric Research)

The data collected during Concordiasi will also improve the understanding of processes driving ozone-hole formation each spring in the Southern Hemisphere. Toward that end, the fall 2010 Concordiasi program flew 13 driftsondes from McMurdo, the main U.S. research base in Antarctica. Fitted with as many as 52 miniature dropsondes, the driftsondes transmitted detailed atmospheric information via satellite to a ground-based station in real time.

While such a capability may seem conventional, reliable real-time satellite data transfer has only recently become viable globally. Although the driftsonde system was developed for the African Monsoon Multidisciplinary Analyses project in 2006, Concordiasi offered an opportunity to enhance remote operations, real-time data download capabilities, and the rapid uploads that feed operational weather models. The team also improved driftsonde technology to allow the systems to function aloft over the span of several months.

During Concordiasi, operators on the ground vetted atmospheric data soon after driftsonde transmittal, running the data through quality-control procedures before uploading it to the Global Telecommunications System. The Global Telecommunications System is a World Meteorological Organization effort that improves the collection, exchange and distribution of weather observations and data. Once in the system, Concordiasi data were used by operational models at research centers around the world responsible for creating near-real-time weather forecasts.

Understanding atmosphere

The 639 dropsonde profiles collected during the Concoridiasi Project provide an unprecedented spatial data set over Antarctica. They offer valuable data for future atmospheric research in this region of the world.

Several spin-off developments have benefitted from the work. Among those is perfecting technology created by EOL engineers for a dropsonde system on NASA's Global Hawk, an unmanned aerial vehicle that, like the driftsonde, flies at stratospheric altitudes to collect data that would otherwise not be accessible to researchers.

The technology also allows real-time dropsonde release and download of data from a ground station — driftsonde technology development led to that capability. Additionally, EOL developed a miniaturized dropsonde technology specifically for the driftsondes; the smaller dropsondes will prove useful for future research campaigns on manned aircraft. Coming soon, a new dropsonde system is under development for use on the Gulfstream V research airplane developed by the National Center for Atmospheric Research. The new system will automate GV dropsonde launches; currently an operator manually launches the dropsondes.

"This upgrade is a huge step forward," Cohnsaid. "Today, safety demands that during excessive turbulence, operators remain in their seats on the GV — this means the sondes don't launch. Automating the launch gives scientists and staff who operate the system greater control over dropsondes."

Editor's Note: The researchers depicted in Behind the Scenes articles have been supported by the National Science Foundation, the federal agency charged with funding basic research and education across all fields of science and engineering. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. See the Behind the Scenes Archive.