Sampling While Soaring


On Monday Oct. 26, one of the world’s most expensive jets (roughly $75 million) will depart on a 27-day expedition to survey the entire globe for greenhouse gases in the atmosphere. Outfitted with the most sophisticated air sampling equipment available today, the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER), will carry scientists from Harvard, Princeton, University of Miami, Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration on a 27-day sampling expedition that will travel from Colorado to the Arctic, to the Antarctic, and back.  The mission is nicknamed "HIPPO" - that's "HIAPER Pole-to-Pole Observations."

The plane, a Gulfstream V, is better known for its preference among corporate executives (remember the big three auto execs' notorious trip to D.C. last winter?), but its long-range capabilities and versatility make it a precise research vessel. Owned by the National Science Foundation and operated by NCAR, the plane can travel about 7,000 miles without refueling and can ascend and descend elevations easily. During the expedition, it will fly in an "M" pattern, dropping from about 45,000 feet to about 1,000 feet to take samples from every layer of the atmosphere. Ultimately, this project will provide the first global picture of carbon dioxide and other greenhouse gases, said Dr. Steve Wofsy, HIPPO mission principal investigator, Harvard University.

“Thirty years ago, everyone thought the atmosphere was fixed,” said Wofsy. “It was unimaginable that humans could have affected the concentrations of carbon dioxide, methane, and other greenhouse gases. Now we know we have, and this research will take a snapshot of the earth and see how those gases are distributed over the whole globe.”

A Packed Itinerary

The flights will travel from Colorado to Anchorage, Alaska, and the Arctic Circle before heading south across the Pacific Ocean to New Zealand and Antarctica.

First-Of-A-Kind Measurements

Specifically, HIPPO will measure cross sections of atmospheric concentrations from the north to south poles, sampling air at elevations that vary from sea level to 45,000 feet. By sampling a cross-section of the atmosphere, the scientists will record a comprehensive picture that satellites cannot capture, said Wofsy. The air sampling equipment makes a measurement every second.

National Center For Atmospheric Research co-PI Britt Stevens adjusts equipment aboard the Gulfstream V. Photo: Courtesy UCAR
National Center For Atmospheric Research co-PI Britt Stevens adjusts equipment aboard the Gulfstream V. Photo: Courtesy UCAR

Simple Physics and Complicated Physics

Preparing the plane’s machinery demanded dedicated focus from physicists and engineers charged with quality control and quality assurance. With powerful computers, two laser spectrometers, and other extremely advanced instruments designed specifically for the HIPPO project, scientists will be able to measure CO2 and other gases in real time, instead of collecting a number of samples in flasks for later analysis in a lab. The location of the air intake chambers was carefully designed to avoid collecting fuel emissions from the jet.

Model Improvement

Scientists on board will be able to glean insight from the data as it loads into their computers, Wofsy said. But detailed analysis and measurements will take about six to eight months. That information will be used to improve existing computer models that measure the output, location, and concentration of greenhouse gases.

“Once the models are improved, we’ll go back to see who is doing what [to send greenhouse gases into the atmosphere], and how much are they contributing,” said Wofsy.

Such information could prove relevant should a global climate change treaty emerge that calls on nations to substantially curb their emissions. In addition, the team will study how logging and regrowth in the boreal and tropical rain forests, as well as changes in the upper atmospheric winds around Antarctica, are affecting levels of CO2 in the atmosphere.


In addition to CO2, scientists will analyze other gases and atmospheric particles, such as methane, whose concentrations have tripled since the Industrial Age and appear to be rising.

“HIPPO is the first time that atmospheric scientists can get a complete picture of over 30 trace gases and black carbon aerosols that influence climate,’ said James Elkins, a NOAA scientist working on the project.


Bird's eye view: Looking down as the GV descends during the January 2009 expedition onto a snowy runway. Photo: Courtesy UCAR
Bird's eye view: Looking down as the GV descends during the January 2009 expedition onto a snowy runway. Photo: Courtesy UCAR

Plus, the expedition will be fun. This is the second research flight and third journey for the aircraft, which underwent a proof of concept trial run in 2008 to demonstrate the vessel’s viability. The first expedition in January 2009 went well, and, following this trip, HIAPER will fly again in April 2010 and twice in the summer of 2011.

“Essentially, we’re taking our flying laboratory around the world and measuring as we go,” Wofsy said.