A New View of Arctic HazeJim Crawford

NASA Langley Research Center

Asia

NorthAmerica

Europe

Fires

Urgent Need to Better Understand Changes in Urgent Need to Better Understand Changes in the Arctic Atmospherethe Arctic Atmosphere

• Receptor and accumulator of pollution from Receptor and accumulator of pollution from northern mid-latitudes continentsnorthern mid-latitudes continents

• Increasing forest fires in Siberia, Canada, Increasing forest fires in Siberia, Canada, Alaska blanket large areas with smokeAlaska blanket large areas with smoke

• Rapid warming over the past decades – Rapid warming over the past decades – faster than anywhere else on Earthfaster than anywhere else on Earth

• Arctic haze and other pollution may be an Arctic haze and other pollution may be an important contributor to the warming, with important contributor to the warming, with complicated feedbackscomplicated feedbacks

Our goal is to test and improve the models used to Our goal is to test and improve the models used to predict changes in Arctic pollution and climatepredict changes in Arctic pollution and climate

THE ARCTIC IS A BEACON OF GLOBAL CHANGE

DC-8P-3BB200

Arctic Research of the Composition of the Troposphere Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS)from Aircraft and Satellites (ARCTAS)

Flights during Spring (Arctic Haze) and Summer (Boreal Fires)Flights during Spring (Arctic Haze) and Summer (Boreal Fires)

High Spectral Resolution Lidar Observations of Arctic Haze from the NASA B200 aircraft

cloud

cloud

Long-range transport from mid-latitudes into the Arctic results in an aerosol haze (blue) that is mixed throughout the troposphere.

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0

Alt

itu

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100806040200Aerosol Extinction (Mm

-1)

Median

10th

and 90th

Percentile

0.100.050.00

Black Carbon (g/m3)

Aerosol Extinction

Intense aerosol plumes originating from fires were superimposed on the background Arctic haze.

How important are they relative to the background haze?

Anomalies in fire counts and carbon monoxide corroborate unusually strong fire emissions over Siberia in April 2008.

CALIPSO (observations)

GMAO (model)

RAQMS (model)

Eastern Asia (110E – 130E)

CALIPSO observations suggest that model transport of aerosols to the Arctic from Siberian fires is too strong.

Sharp gradient observed by CALIPSO not seen in model predictions.

Why?Emissions?Scavenging?

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1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Area Burned over Time (M ha)

Russia

Canada andAlaska

Although ARCTAS observations show a larger than expected contribution from fire emissions in spring, this may not be inconsistent with recent trends in boreal fires.

Early results from an inverse modeling study of carbon monoxide suggest that a reduction in estimated fire emissions by factors of 2 to 3 is required to match observed levels.

Model sensitivity to scavenging assumptions are also being evaluated.