air pollution in the us : ozone and fine particulate matter (pm 2.5 ) are the two main pollutants
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AIR POLLUTION IN THE US : Ozone and fine particulate matter (PM 2.5 ) are the two main pollutants. 75 ppb (8-h average). 15 m g m -3 (1-y av.). http://epa.gov/airtrends/2010/. PM 2.5. Ozone. Ozone air quality standards in the US and in the world. Canadian AQS (8-h avg.). Europe AQS - PowerPoint PPT PresentationTRANSCRIPT
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AIR POLLUTION IN THE US :Ozone and fine particulate matter (PM2.5) are the two main pollutants
75 ppb (8-h average)15 g m-3 (1-y av.)
http://epa.gov/airtrends/2010/
OzonePM2.5
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0 20 40 60 80 100 120 ppb
Europe AQS(seasonal)
U.S. AQS(8-h avg.)
U.S. AQS(1-h avg.)
Preindustrialozone
background
Present-day ozone background at
northern mid-latitudes
Europe AQS (8-h avg.)
Canadian AQS (8-h avg.)
Mexican AQS(1-h avg.)
Ozone air quality standards in the US and in the world
20082014? 1997
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4th-highest annual maximum for daily 8-h average ozone,2008-2010
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OZONE CONCENTRATIONS vs. NOx AND VOC EMISSIONSAir pollution model calculation for a typical urban airshed
NOx-saturated
NOx-limited Ridge
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LARGE SUPPLY OF BIOGENIC VOCs – unrecognized until the 1990s
Isoprene (biogenic VOC)Anthropogenic VOCs
Jacob et al., 1993
Switches polluted areas in U.S. from NOx-saturated to NOx-limited regime!recognized in Revised Clean Air Act of 1999
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MAPPING OF VOC EMISSIONS FROM SPACEusing satellite measurements of formaldehyde
confirms dominance of biogenic over anthropogenic VOCs
Millet et al. [2008]
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1970-2003 TREND OF U.S. EMISSIONS
Focus until past decade was on VOC emission controls
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OZONE TRENDS IN U.S. http://www.epa.gov/airtrends/
Boston trend
National trend
• The national trend is heavily weighted by California sites;• other parts of the country have seen marginal improvement
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DECREASE OF POWER PLANT NODECREASE OF POWER PLANT NOx x EMISSIONS EMISSIONS
OVER THE PAST DECADEOVER THE PAST DECADE
Decreasing US NOx emissions from power plants
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Decrease of North American NOx emisssions, 2005-2009
as seen with annual mean NO2 columns from the OMI satellite instrument
Shailesh Kharol (Dalhousie)
20092005
Decreases in both the eastern US and eastern Canada
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EVEN IN NOEVEN IN NOxx-LIMITED REGIME,-LIMITED REGIME,
THE THE TOTALTOTAL O O33 PRODUCED IS ONLY A WEAK FUNCTION OF NO PRODUCED IS ONLY A WEAK FUNCTION OF NOxx
NO NO2 HNO3hv
HO2,RO2,O3 OH, O3
P(O3) L(NOx)
3 5 2 4
8 2 8 2
( ) 2 [ ][ ] 2 [ ]
( ) [ ][ ] [ ] OPE =
x
P O k HO NO k VOC
L NO k NO OH k NO
Emission Deposition
Assuming NOx steady state, efficient HOx cycling, and loss of NO2 by reaction with OH:
OPE as NOx strong nonlinearity; in models, decreasing NOx emissionsby 50% reduces ozone only by ~15%
Define ozone production efficiency (OPE) as the total number of O3 molecules produced per unit NOx emitted.
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MEAN AFTERNOON SUMMER OZONE (2006)
ppb
CASTNet sites (regional background)
High ozone concentrations at sites in intermountain west
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8-h daily maximum ozone in the intermountain West (2006)
56.3 ppb 53.2 ppb12.3 ppb
58.1 ppb 56.4 ppb
15.0 ppb
GEOS-Chem model US pollutioncontribution
Zhang et al., 2011
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North American ozone background over the US
4th highest annual North American background ozone (GEOS-Chem model)
Zhang et al. [2011]
defined as the surface ozone concentrations that would be present in the absence of North American anthropogenic emissions
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Decrease of North American NODecrease of North American NOx x emisssions, 2005-2009 emisssions, 2005-2009
as seen with annual mean NO2 columns from the OMI satellite instrument
Shailesh Kharol (Dalhousie)
20092005
Decreases in both the eastern US and eastern Canada
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Daytime surface ozone distributions, 2006-2010
Spring SummerCooper et al. [2012]
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Daytime surface ozone trends, 1990-2010
Spring SummerCooper et al. [2012]
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Using OMI observationsto monitor growth in emissions from Canadian oil sands
Oil sand recoveryIn Alberta
OMI NO2 columns, 2004-2010
NO2 increase of 10.4 ±3.5% per year
McLinden et al. [GRL 2012]
AQAST PI: DIckerson
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Ozone trends in remote air at northern mid-latitudes
D.D. Parrish, NOAA
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Rising surface ozone pollution in China
D.D. Parrish, NOAA
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INTERCONTINENTAL OZONE POLLUTION INFLUENCESINTERCONTINENTAL OZONE POLLUTION INFLUENCES
Surface O3 enhancements from North American anthropogenic emissions
from European anthropogenic emissions
from Asian anthropogenic emissions
Lin Zhang, Harvard
GEOS-Chem model results for 2006