13 March 2008
As a part of the International Polar Year research, NOAA scientists and their U.S. and international colleagues will conduct the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) field study. ARCPAC is an airborne research activity to investigate the climate-changing characteristics of pollution in the Arctic. The ARCPAC work will be a part of the international POLARCAT research activity (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport). Scientists from the ESRL Chemical Sciences Division are leading the effort, and scientists from ESRL Global Monitoring Division and NESDIS are among the participants.
Observations from the ground, from balloons, and from satellite all show that the Arctic is warming faster than the average across the globe. Sea ice cover in summertime has decreased in extent by about 40% relative to the 1979-2000 average, and the concentration and thickness of the sea ice are also decreasing. ARCPAC will investigate the possible connections between pollution such as atmospheric fine particles (aerosol, the "Arctic Haze"), clouds, and the melting of polar ice in the region.
ARCPAC observations will take place during the first ~3 weeks of April 2008 and will use a NOAA WP-3D research aircraft based at Fairbanks, Alaska. A suite of instruments onboard will make extensive measurements of atmospheric trace gases, aerosol particles, clouds, solar radiation, and meteorology. The experiment will be coordinated with the POLARCAT activity of the IPY, with the NOAA baseline climate research station at Barrow, Alaska, and with the intensive operations period executed at the DOE-sponsored Atmospheric Radiation Measurement site adjacent to NOAA's Barrow site. The relatively aged aerosol pollution studied during ARCPAC will also be compared with the pollution studied during the NOAA-led International Chemistry Experiment in the Arctic Lower Troposphere (ICEALOT) campaign (also in April), which will provide shipboard measurements of atmospheric aerosol and trace gas pollution in the North Greenland and Barents Seas, closer to the pollution sources.
Background: The long-range transport of anthropogenic pollution from North America, Europe, and western Asia creates the aerosols associated with the so-called Arctic Haze, a phenomenon that recurs every winter and spring. Ozone and aerosol fine particles are produced in the atmosphere when pollutants mix and react in the presence of sunlight. The direct and indirect climate impact of the aerosols can be quite different in the Arctic compared to elsewhere, because the high surface reflections from snow and ice mean that even weakly absorbing aerosol layers can heat the Earth/atmosphere system in the Arctic. Aerosol particles may change the radiative characteristics of clouds in the Arctic and make them more effective insulators. And since some soot is deposited to the surface and darkens the snow, soot may warm both the atmosphere and the surface when the sun rises in springtime.
Significance: This research will help provide information regarding a question that is foremost among the minds of decision makers, the public, and the scientific community. Namely, why is the Arctic sea ice melting faster than expected? Anticipated payoffs of the research include:
The research contributes to the Understanding Climate Processes capability within the Climate Research and Modeling Program of NOAA's Climate Goal.