Tracking pollution in the Arctic atmosphere Jenny A. Fisher Earth & Planetary Sciences Day April 25, 2009 Word of the Day: Sources Image Courtesy Cam McNaughton
Arctic Facts Remote Cold & Icy Clean Home to Polar Bears
Arctic Facts or Fictions? Remote Norilsk Smelter West Siberian Oil Fields Cold & Icy Prudhoe Bay Oil Fields Alberta Tar Sands Clean Home to Polar Bears
Where does the pollution come from? Surface observations showed: But models have shown: 1980s 2003 2005 2008 Barrie and Hoff, 1985; Barrie, 1986; Klonecki et al., 2003; Koch and Hansen, 2005; Shindell et al., 2008
Surface, aircraft, and satellite observations provide complementary information Surface: long term records, but sparse in time and space, only observe boundary layer Aircraft: high resolution at all levels, but short, infrequent, limited spatial coverage Satellites: nearly global daily coverage, continuous records, but limited sensitivity, difficult to interpret
Global models provide the link between these disparate data sources AIRCRAFT MODEL SATELLITE SURFACE
Carbon monoxide (CO) can be used to track pollution CO Sources: Fossil fuels Biomass burning AIRS CO, May 2004 Observable: CO can be observed in situ by aircraft and remotely by satellites Simple chemistry: only loss is through reaction with OH Intermediate length lifetime: long enough to follow plumes short enough to distinguish from background
ARCTAS (April 2008) provided a unique dataset ARCTAS Arctic Research of the Composition of the Troposphere from Aircraft and Satellites Coordinated aircraft campaign (NASA + NOAA + DOE + Europeans + ) Simultaneous intensive surface sampling Polar orbiting satellites, especially AIRS, provided continuous satellite data
What made April 2008 interesting? Arctic pollution peaks in April Sulfate aerosol Feb Apr Jun Scheuer et al., 2003 Satellite data quality improves in spring Extremely large & early fires in Russia in April 08 Fire Pixel Counts = April 1σ mean 2002 2003 2004 2005 2006 2007 2008 NASA GESDISC NASA GEOS Chem CO emissions
GEOS Chem model performance during ARCTAS GEOS Chem and aircraft CO profiles GEOS Chem and ground based CO columns from Eureka, Canada AIRS GEOS Chem % Diff. 20 0 20 %
Reduce the model bias by improving the sources Least squares fit between observed and modeled CO tagged by source A priori, R=0.36 A posteriori, R=0.69 GEOS Chem underestimates: North American fossil fuel 4% European fossil fuel 39% Asian fossil fuel 23% GEOS Chem overestimates: Russian biomass burning 79% Asian biomass burning 68%
Scaling modeled sources improves agreement with data
Pollution plumes during ARCTAS from: North America (April 5, 2008) Back trajectories show sources
Pollution plumes during ARCTAS from: Russian fires (April 16, 2008) Back trajectories show sources
Pollution plumes during ARCTAS from: Europe (April 17, 2008) Back trajectories show sources
GEOS Chem shows the importance of different sources At low altitude (2 km): European and Asian fossil fuel dominate Arctic Russian fires affect Alaska
GEOS Chem shows the importance of different sources At mid altitude (5 km): Asian fossil fuel becomes dominant Russian fires still impact Alaska
GEOS Chem shows the importance of different sources At high altitude (8 km) Asian fossil fuel still dominates Asian biomass burning begins to play a role
AIRS satellite record provides context for 2008 results Mean AIRS CO, April 2008 Lower than average CO over Alaska Mean difference in AIRS between April CO in 2008 and mean April CO for 2002 2008 High CO from fires Increased export from Europe Courtesy M. Purdy Why the differences? See Meghan Purdy s senior thesis talk on May 6 th!
In summary, haiku style: 1. Arctic pollution: Makes a big mess in the spring. What are the sources? 4. We saw many plumes: Russia, Europe, U.S.A.: Everyone s to blame. 2. Satellites can help, We need planes and ground sites too. Models link them all. 5. At low altitude, Pollution is mostly from Europe and Asia. 3. Model has bias: Not enough fossil fuels, and Too many big fires! 6. At high altitude, Asian CO dominates It is everywhere! Thanks to: Glenn Diskin, Juying Warner, and the rest of the ARCTAS Science Team Meghan Purdy, Monika Kopacz, Daniel Jacob and the rest of the Atmospheric Chemistry Modeling Group