Wednesday, December 16, 2009

NASA Gets Up-Close Look at Far Corner of the Globe

NASA's DC-8 casts a shadow on Arctic ice during a campaign in 2008 to measure the presence of pollution from mid-latitude continents and smoke and soot from wildfires in the Arctic atmosphereThe Arctic remains in the mind a pristine wonderland. The landmasses that jut into the Arctic Circle are covered by tundra and primeval forest; the pole is covered in ice. The whole environment seems detached from human influence entirely. But the scientific record tells a different story.

A months-long airborne campaign in 2008 gave scientists a new look at how everyday human behaviors in Europe, North America and Asia are affecting the Arctic, the most rapidly changing region on Earth and a major regulator of the planet's climate. The data show human fingerprints all over the Arctic in the form of polluted exhaust from factories and smoke from fires often set by human hands. Observations from the ground have long recorded some of this impact, and satellites in low-earth orbit provide a different view, but scientists had not undertaken a detailed, airborne study of this magnitude in years.

The mission provided a new view of how pollution from industrializing Asian countries influences the Arctic. Ground sensors have long detected the regular, low-altitude movement of polluted air masses from Europe to the Arctic. Because of the colder temperatures in the countries of the pollution's origin, the plumes of carbon dioxide, carbon monoxide and other warming-related gases do not rise high in the atmosphere. On the contrary, pollution from warmer regions in Asia has apparently been moving to altitudes too high for ground instruments to observe well. The airborne instruments provided invaluable measurements of the extent of this pollution, said Daniel Jacob, a Harvard University atmospheric scientist and both mission scientist and co-principal investigator for NASA’s Arctic Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission.

"With Asian pollution, there's a relatively warm ocean immediately downwind of a fairly cold continent, so you have interesting storm tracks that lift pollution and transport it at higher altitudes," Jacob said. "It's certainly a much larger influence on Arctic haze than what had been traditionally ascribed."

Now that researchers have had some time to sift through the data collected, Jacob said the value of these observations is coming in to focus. Major airborne campaigns like this are rare, so almost any study of the Arctic atmosphere in coming years will draw on ARCTAS.

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