From Pole to Pole
HIPPO Mission: a global picture of the atmosphere, greenhouse gases
Carbon dioxide and other pollutants are higher in concentration over the Arctic than many scientists expected, and more oxygen is piling up over the Southern Ocean, according to initial data from HIPPO, a multiagency, multiyear mission to paint a three-dimensional portrait of the atmosphere.
In January, a modified corporate jet took a roller-coaster tour of the planet, looping from pole to pole with two ESRL scientists among those on board, and five ESRL instruments. Researchers captured the most detailed measurements yet of greenhouse gases, ozone, particles, and other atmospheric constituents, from 78oN to 68oS latitude and 0 to 15 km altitude. That information is critical for both climate modelers seeking to understand Earth’s future, and policy makers, who rely on accurate science for decision making.
Led by Harvard University’s Steve Wofsy, HIPPO is jointly operated and supported by the National Science Foundation, the National Center for Atmospheric Research, and NOAA ESRL. The mission was designed to fill the relatively empty observation space between satellites—which often can’t profile the vertical structure of the atmosphere—and the ground-based instruments of ESRL’s Global Monitoring Division and other networks.
“We’re bridging that gap,” said Jim Elkins, a HIPPO co-investigator and scientist with ESRL’s Global Monitoring Division. “We’ve had some flights over parts of North America, and some satellites give broad coverage of the stratosphere, but they can have trouble getting down into the troposphere,” Elkins said.
An early look at HIPPO data suggests great success, he said. “We got a cross-section of the atmosphere, up and down, from pole to pole. We have never done this before.”
During January’s journey, a series of 11 flights spanning the globe, HIAPER dipped to within a few hundred feet of the ground and ocean, and soared up into the lower stratosphere, 45,000 feet high. The mission was the first of what will be five globe-spanning journeys in the next three years, spread out among seasons and focused on areas that are not well sampled, especially the Southern Hemisphere and oceans.
“We’d really like to know more about the budgets of greenhouse gases and black carbon particles, the sources and sinks of these materials on the surface of the Earth, how they get into the atmosphere, how they get moved around,” Wofsy said during a press conference after January’s flights. “If people are going to actually make treaties that ban or restrain the use of these materials, those treaties have to be based on sound scientific knowledge.”
NCAR’s Britt Stephens told reporters that the CO2 piling up in the Arctic is likely a result of industrial emissions from the Northern Hemisphere and the wintertime “exhaling” of the terrestrial biosphere. The slightly higher-than-expected oxygen measured over the Southern Ocean may help researchers better understand carbon dynamics in that understudied region, Stephens said.
Fred Moore from ESRL’s Global Monitoring Division, and Josh Schwarz from the Chemical Sciences Division flew on HIPPO. Schwarz was responsible for a Soot Particle Photometer, SP2, which measures black carbon particles—the instrument was on its first global mission. Black carbon can absorb solar radiation and warm the surrounding atmosphere. “It could have a lot of radiative effects, globally, but it hasn’t yet been studied extensively,” Schwarz said.
HIPPO’s third set of flights was expected to provide “ground truthing” support for NASA’s Orbiting Carbon Observatory, OCO, which failed during launch in February. OCO’s loss makes HIPPO data even more valuable, said David Fahey, with ESRL’s Chemical Sciences Division and a member of the HIPPO science team. “The datasets are stunning,” Fahey said. “These are pseudo-satellite profiles of important gases and particles across a vast region of the remote atmosphere.”
The scientists who flew on HIPPO said the first leg of the mission was a stunning one visually, as well. “It’s quite an experience to fly an airplane at one point in time above the ice sheets, above the floating ice in the Arctic Ocean, with the waves there and the moonlight illuminating it, and then a short while later to be in American Samoa, a tropical paradise and then a short while later, in New Zealand, and a short while after that in the Southern Ocean,” Wofsy said. “It really gave us a tremendous aesthetic impression of the whole atmosphere and the connectedness of the globe.”