NASA - National Aeronautics and Space Administration

The B-200 from NASA's Langley Research Center is one of three aircraft outfitted with scientific instruments to collect atmospheric data during Arctic flights in April 2008. Credit: NASA
> Larger image The recent decline of Arctic sea ice is one indication that this region is undergoing significant environmental changes related to climate warming. To investigate the atmosphere's role in this climate-sensitive region, NASA and its partners have begun the most extensive field campaign ever to study the chemistry of the Arctic's lower atmosphere.

The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign is poised to help scientists identify how air pollution contributes to climate changes in the Arctic.

The campaign begins this week in Fairbanks, Alaska. Three NASA research aircraft -- the DC-8, P-3 and B-200 -- will serve as airborne laboratories for the next three weeks, carrying instruments to measure air pollution gases and aerosols and solar radiation. Of particular interest is the formation of the springtime "arctic haze," which is fueled by sunlight causing chemical reactions of pollutants accumulated over the winter from long-range transport from lower latitudes.

"It's important that we go to the Arctic to understand the atmospheric contribution to warming in a place that's rapidly changing," says Jim Crawford, manager of the Tropospheric Chemistry Program at NASA Headquarters, Washington. "We are in a position to provide the most complete characterization to date for a region that is seldom observed but critical to understanding climate change."

"The Arctic is a poster child of global change, and we don't understand the processes that are driving that rapid change," says Daniel Jacob, an ARCTAS project scientist at Harvard University, Cambridge, Mass. "We need to understand it better, and that's why we're going."

Chris Cantrell and Becky Anderson of the National Center for Atmospheric Research, Boulder, Colo., assess an instrument’s operation on NASA's DC-8 aircraft during preparations for the ARCTAS field campaign. Credit: NASA
> Larger image The wealth of data collected will also improve computer models used to study global atmospheric chemistry and climate. This will ultimately provide scientists with a better idea of how pollutants are transported to and around the Arctic and their impact on the environment and climate.

"We haven't looked at pollution transport in a comprehensive fashion," says Hanwant Singh, an ARCTAS project scientist at NASA Ames Research Center, Moffett Field, Calif. "We can see arctic haze coming in, but we don’t know its composition or how it got there. One goal of ARCTAS is to provide a comprehensive understanding of the aerosol composition, chemistry, and climate effects in the Arctic region."

The new aircraft observations will also help researchers interpret data from NASA satellites orbiting over the Arctic, such as Aura, Terra, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Interpreting satellite data can be difficult in the Arctic due to extensive cloud cover, bright reflective surfaces due to snow and ice, and cold surface temperatures. For example, it's difficult for researchers to look at satellite data and distinguish between light reflected by clouds and light reflected from white ice cover.

This image illustrates how the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite obtains a vertical slice of atmospheric data, used to study the nature of the atmosphere. Credit: NASA
> Images and animations from the Conceptual Image Lab "NASA has invested a lot of resources in satellites that can be of value for diagnosing effects of climate change,” Jacob says. "Satellites orbit over poles with good coverage and good opportunity, but you really need to have aircraft observations supporting those to make good interpretations of what satellites are telling you," he said.

The new airborne view of the Arctic atmosphere combined with satellite data will provide scientists with a better understanding of the atmospheric side of the climate question. "We're interested in data that will help models better characterize the current state of the atmosphere – to set a benchmark for them so we can gain confidence in their ability to predict future warming in the Arctic," Crawford says.

A second phase of the ARCTAS campaign takes place this summer from Cold Lake in Alberta, Canada, where flights will focus on measurements of emissions from forest fires. Researchers want to know how the impact of naturally occurring fires in the region compares to the pollution associated with human activity at lower latitudes. Understanding the relative influence of each is important to predictions of the Arctic's future climate.

Related links:

> NASA's ARCTAS Web site
> NASA's IPY Web site Kathryn Hansen
NASA's Goddard Space Flight Center