Transcript Intercontinental Air Pollution and the Great Lakes Region

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)
April, 2001 Sulfate from GLR
Lake effect
high O3
June
July
August
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
Air Quality in the Great Lakes
High PM in both Winter and
Summer
Chicago, Illinois
PM2.5 = 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