by Judith Curry
NCAR/UCAR has issued a press release: “First global portrait of greenhouse gases emerges from pole-to-pole flights.”
BOULDER–A three-year series of research flights from the Arctic to the
Antarctic has successfully produced an unprecedented portrait of
greenhouse gases and particles in the atmosphere, scientists announced
today. The far-reaching field project, known as HIPPO, is enabling
researchers to generate the first detailed mapping of the global
distribution of gases and particles that affect Earth’s climate.
The series of flights, which come to an end this week, mark an important
milestone as scientists work toward targeting both the sources 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
The three-year campaign has relied on the powerful capabilities of a
specially equipped Gulfstream V aircraft, owned by the National Science
Foundation (NSF) and operated by NCAR. The research jet, known as the
High-performance Instrumented Airborne Platform for Environmental
Research (HIAPER), has a range of about 7,000 miles (11,000 kilometers).
It is outfitted with a suite of specially designed instruments to sample
a broad range of atmospheric constituents.
The flights have helped scientists compile extraordinary detail about
the atmosphere. The research team has studied air samples at different
latitudes during various seasons from altitudes of 500 feet (150 meters)
above Earth’s surface up to as high as 45,000 feet (13,750 meters), into
the lower stratosphere.
HIPPO, which stands for HIAPER Pole-to-Pole Observations, brings
together scientists from organizations across the nation, including
NCAR, Harvard University, the National Oceanic and Atmospheric
Administration (NOAA), Scripps Institution of Oceanography, the
University of Miami, and Princeton University. NSF, which is NCAR’s
sponsor, and NOAA are funding the project.
—–Surprises on the way to a global picture—–
The first of the five HIPPO missions began in January 2009. Two
subsequent missions were launched in 2010, and two in 2011. The final
mission comes to an end on September 9, as the aircraft returns from the
Arctic to Anchorage and then to its home base at NCAR’s Research
Aviation Facility near Boulder.
Each of the missions took the research team from Colorado to Alaska and
the Arctic Circle, then south over the Pacific to New Zealand and near
Antarctica. The flights took place at different times of year, resulting
in a range of seasonal snapshots of concentrations of greenhouse gases.
The research was designed to help answer such questions as why
atmospheric levels of methane, a potent greenhouse gas, have tripled
since the Industrial Age and are on the rise again after leveling off in
the 1990s. Scientists also studied how logging and regrowth in northern
boreal forests and tropical rain forests are affecting levels of carbon
dioxide (CO_2 ) in the atmosphere. Such research will provide a baseline
against which to evaluate the success of efforts to curb CO_2 emissions
and to enhance natural CO_2 uptake and storage.
The team measured a total of over 80 gases and particles in the atmosphere.
One of HIPPO’s most significant accomplishments has been quantifying the
seasonal amounts of CO_2 taken up and released by land plants and the
oceans. Those measurements will help scientists produce more accurate
estimates of the annual cycle of carbon dioxide in and out of the
atmosphere and how the increasing amount of this gas is influenced by
both the natural world and society.
The team also found that black carbon particles—emitted by diesel
engines, industrial processes, and fires—are more widely distributed in
the atmosphere than previously thought. Such particles can affect
climate in various ways, such as directly absorbing solar radiation,
influencing the formation of clouds or enhancing melt rates when they
are deposited on ice or snow.
“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.”
Researchers were also surprised to find larger-than-expected
concentrations of nitrous oxide high in the tropical atmosphere. The
finding has significant environmental implications because the gas both
traps heat and contributes to the thinning of the ozone layer. Nitrous
oxide levels have been increasing for decades in part because of the
intensive use of nitrogen fertilizer for agriculture. The abundance of
the gas high in the tropical atmosphere may be a sign that storms are
carrying it aloft from sources in Southeast Asia.
—–Balancing the carbon budget—–
The task of understanding how carbon cycles through the Earth system,
known as “balancing the carbon budget,” is gaining urgency as policy
makers discuss strategies to limit greenhouse gases. Some countries or
regions could be rewarded with carbon credits for taking steps such as
preserving forests believed to absorb carbon dioxide.
“Carbon markets and emission offset projects are moving ahead, but we
still have imperfect knowledge of where human-emitted carbon dioxide is
ending up,” NCAR’s Stephens says.
Before HIPPO, scientists primarily used ground stations to determine the
distribution of sources of atmospheric CO_2 and “sinks” that reabsorb
some of the gas back into the land and oceans. But ground stations can
be separated by thousands of miles, which hinders the ability to measure
CO_2 in specific locations. To estimate how the gas is distributed
vertically, scientists have had to rely on computer models, which will
now be improved with HIPPO data. END
Details on the HIPPO project can be found at the project web site.
The overview publication by S.C. Wofsy can be found here.
JC comment: This is an important project that has the potential to sort out many issues related to greenhouse gases and their spatial and temporal variations.