HIPPO – HIAPER Pole-to-Pole Observations – is the name of an unprecedented three-year series of research flights from the Arctic to Antarctica which has provided scientists with a first of its kind portrait of greenhouse gases and particles in the atmosphere.
This week marks the end of HIPPO’s last flight, and provide researchers with the data to create detailed mapping of the global distribution of gases and particles that affect Earth’s climate, and will hopefully provide scientists with the data to finally target both the source of greenhouse gases and the natural processes that draw the gases back out of the atmosphere.
“Tracking carbon dioxide and other gases with only surface measurements has been like snorkeling with a really foggy mask,” says Britton Stephens, a scientist with the National Center for Atmospheric Research (NCAR) and one of the project’s principal investigators. “Finally, HIPPO is giving us a clear view of what’s really out there.”
“With HIPPO, we now have views of whole slices of the atmosphere,” says Steven Wofsy, HIPPO principal investigator and atmospheric and environmental professor at Harvard University’s School of Engineering and Applied Sciences. “We’ve been quite surprised by the abundance of certain atmospheric components and the locations where they are most common.”
The HIPPO campaign was carried out using a specially equipped Gulfstream V aircraft owned by the National Science Foundation and operated by the National Center for Atmospheric Research. Known as the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER for short, thankfully), has a flying range of 11,000 kilometres (7,000 miles) and is outfitted with a suite of specially designed instruments that allow researchers to better sample the broad range of atmospheric constituents along its flight path.
There were five HIPPO missions in total; one beginning in January of 2009, another two launched throughout 2010 and the final two in 2011. The flights took place at different times of the year so that the researchers could sample a range of seasonal snapshots of concentrations of greenhouse gases in an effort to determine why atmospheric levels of methane have tripled since the Industrial Age and are on the rise again after having levelled off during the 90s.
The researchers also studied how logging and regrowth in the northern boreal forests and tropical rainforests are affecting atmospheric carbon dioxide levels.
So far, HIPPO has managed to quantify the seasonal amounts of carbon dioxide taken up and released by land plants and the oceans, which will allow scientists to produce more accurate estimates of the annual cycle of carbon dioxide being pumped in and out of our atmosphere, and how the increase in carbon dioxide is influenced by both humans as well as natural cycles.
The team also found that larger-than-expected concentrations of nitrous oxide exist high in the tropical atmosphere. The team were surprised to find such levels, with significant environmental implications resulting from the discovery, because the gas both traps heat in the atmosphere as well as contributes to the thinning of the ozone layer.
Nitrous oxide levels have increased steadily as a result of the intensive use of nitrogen fertilizer in agriculture, and its abundance in the high atmosphere could be a sign that storms are carrying it aloft from sources in Southeast Asia.
The team also found that black carbon particles – those particles released by diesel engines, industrial processes and fires – are more widely distributed in the atmosphere than had been previously estimated.
“What we didn’t anticipate were the very high levels of black carbon we observed in plumes of air sweeping over the central Pacific toward the U.S. West Coast,” says NOAA scientist Ryan Spackman, a member of the HIPPO research team. “Levels were comparable with those measured in megacities such as Houston or Los Angeles. This suggests that western Pacific sources of black carbon are significant and that atmospheric transport of the material is efficient.”