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Intercontinental Air Pollution and the Great Lakes Region. Tracey Holloway University of Wisconsin--Madison ICAP Meeting; 10/21/04. Talk Overview. Introduction to the Great Lakes Regional Chemistry and Transport in the Great Lakes Intercontinental Transport from the GLR
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Intercontinental Air Pollution and the Great Lakes Region Tracey Holloway University of Wisconsin--Madison ICAP Meeting; 10/21/04
Talk Overview • Introduction to the Great Lakes • Regional Chemistry and Transport in the Great Lakes • Intercontinental Transport from the GLR • Intercontinental Transport to the GLR
Great Lakes Basics • GL contain ~95% of U.S. surface fresh water; ~20% of global surface fresh water • Basin area: 781,000 km2; Lake area: 247,000 km2 • +24M Americans (about 10%), +10M Canadians (about 30%) live in GLR
Great Lakes Meteorology • The high heat capacity of the Great Lakes -> creation of deep convective boundary layers in the winter; shallow in summer
Great Lakes Meteorology • Moisture from the lakes contributes to water vapor content, downstream cloudiness, rainfall, snowfall, and regional storm formation. • Lake effects can be out of phase with seasons: e.g. Lake Erie temperatures warmer than the Buffalo air temperature from midsummer to early spring [Miner and Fritsch, 1997] -> we expect early summer O3 transport and chemistry patterns differ significantly from the late summer patterns
Above-lake high O3 Monitored Ozone Results Modeled Ozone Results LADCO
Characteristics of Great Lakes effects on O3 • Low-level “conduction layers” over the lake promote O3 formation and transport [Dye et al., Sillman et al. 1993]. • Lake breeze circulations contribute to rapid increases in O3 concentrations [Hastie et al., 1999] • Lake temperatures exert a strong influence on above-lake O3 formation [Fast and Heilman, 2003].
Global Effects from GLR? • GLR source for WCB in summer (Eckhardt et al., 2003, J. Clim.; figures from reference) • NA -> Europe advection event originating in the GLR, May ‘99, with species transported at 6-8 km (Trickl et al., 2003, JGR) • High meridional temp. gradient in autumn -> possibly stronger jet stream (Lofgren, 1997, J. Clim.)
Key Issues • How does lake-effect meteorology affect pollutant export? • Does lake-effect chemistry (e.g. high ozone levels) have consequences beyond the region?
Interactions between regional & global chemistry & transport • Global analysis: MOZART-2 (with speciated aerosols, including BC, OC, SO4, NO3) • Regional analysis: CMAQ (CB-IV, MEBI, RADM… although more demanding schemes may offer improved accuracy and perform well on Mac Altivec vector chip)
June July August Lake effect high O3 2002 summer values, NCEP meteorology
Global Effects to GLR? Affected by ICT, as is all of North America. No past studies on how GLR meteorology affects (or doesn’t affect) transport characteristics determining ICT influence. L. Horowitz/GFDL
Key Issues • How does lake-effect meteorology affect pollutant entrainment to the surface? • Does lake-effect chemistry decrease or increase the relative impact of imported pollutants and precursors?
Comparing Impacts of Asian Emissions on August O3 CCM winds, O3 too high
Chicago, IllinoisPM2.5 = 8 ug/m3 PM2.5 = 30 ug/m3
Regional study plans • Work just beginning • Mac OSX CMAQ development • Running with 2002 MM5 meteorology from LADCO
Acknowledgments • Larry Horowitz, Arlene Fiore, and Chip Levy (NOAA GFL) • Computer resources from NOAA GFDL • Scott Spak (UW-Madison) • Maps and photos from Great Lakes Information Network and the NOAA GLERL