April 7, 2009 | About the same time of year that many people head to warmer climes, a group of researchers is hunkered down in northern Alaska.
An OASIS researcher extracts carbon from snow samples.
The international team, which includes almost two dozen NCAR staff (mostly from ESSL/ACD), as well as SOARS protégé Talea Mayo, is conducting the OASIS (Ocean–Atmosphere–Sea Ice–Snowpack) experiment in Barrow. The field project, which is part of International Polar Year, is the most detailed study to date of the chemical and physical exchange processes between the ocean, atmosphere, and cryosphere (Earth's frozen realms).
The researchers will look at how these processes impact atmospheric chemistry, climate, and Earth's ecosystems. They hope to advance scientists' understanding of surface ozone and mercury depletion events, in particular, what initiates these events and keeps them going. They're also looking at the Arctic atmosphere's ability to oxidize trace gases and Arctic aerosol production.
"The Arctic has a very rich and complicated chemistry," says John Orlando, one of the NCAR principal investigators on the project, along with Frank Flocke. "It may be one of the few regions in the troposphere where hydrogen oxide, aerosol, bromine, chlorine, and nitrogen oxide chemistry all intersect."
The Barrow component of OASIS includes 25 separate instruments in operation at the field site, nine led by NCAR scientists. The NCAR contingent is focusing on measuring concentrations and fluxes of key chemicals active in the Arctic's boundary layer, including hydrogen oxide radicals, nitrogen oxide and reactive nitrogen, peroxyacetyl nitrate (PAN), ozone, halocarbons, and aerosols, as well as environmental factors such as radiation.
The project runs from late February through mid-April.
ACD's Kirk Ullmann and Sam Hall remove frost from the optics of instruments used to measure the solar spectra, deriving rates of ozone, nitrogen dioxide, and other important atmospheric constituents. These rates are key to understanding the complex atmospheric chemistry of the Arctic.
A member of the OASIS team collects snow samples near Barrow.
Chasing carbon from pole to pole
In late January, a different team of researchers visited the Arctic—as well as the Antarctic and a host of places in between. The team toured around the Pacific aboard the Gulfstream V (HIAPER) for an ambitious project that seeks to make the most extensive airborne measurements of carbon dioxide and other greenhouse gases to date.
HIPPO (HIAPER Pole-to-Pole Observations) consists of five missions running through mid-2011, the first of which took place January 8–30. Researchers from EOL and science institutions around the nation took HIAPER on a grand tour of the Pacific (see map).
The next four missions will follow similar flight paths but at different times of year, resulting in a collection of seasonal snapshots of greenhouse gas concentrations. The team will be able to construct vertical as well as latitudinal cross-sections, with the aircraft dipping as low as 1,000 feet (300 meters) and soaring as high as 47,000 ft (14,000 m) along its route during HIPPO.
The findings will help scientists determine where and when greenhouse gases enter and leave the atmosphere, a critical prerequisite for taking steps to curb global warming. It will shine light on questions such 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 will be able to analyze other gases and particles in the atmosphere that can affect temperatures by influencing clouds or the amount of solar heat that reaches Earth's surface.
"This mission is providing us with amazing data about carbon dioxide and other greenhouse gases from all over the world," says EOL's Britt Stephens, one of the project's co–principal investigators. "Essentially, we have a flying laboratory that we're taking around the world, sucking in air and doing the measurements as we go."
HIPPO took HIAPER on a three-week circuit around the Pacific that began in Boulder and encompassed Alaska, the Arctic Ocean, Hawaii, American Samoa, New Zealand, Antarctica, Tahiti, Easter Island, and Costa Rica (each shown in numerical order). (Illustration by Steve Deyo, COMET.)
Photo of the Arctic taken from HIAPER during the HIPPO mission.