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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 Presentation
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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
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
4th-highest annual maximum for daily 8-h average ozone,2008-2010
OZONE CONCENTRATIONS vs. NOx AND VOC EMISSIONSAir pollution model calculation for a typical urban airshed
NOx-saturated
NOx-limited Ridge
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
MAPPING OF VOC EMISSIONS FROM SPACEusing satellite measurements of formaldehyde
confirms dominance of biogenic over anthropogenic VOCs
Millet et al. [2008]
1970-2003 TREND OF U.S. EMISSIONS
Focus until past decade was on VOC emission controls
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
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
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
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.
MEAN AFTERNOON SUMMER OZONE (2006)
ppb
CASTNet sites (regional background)
High ozone concentrations at sites in intermountain west
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
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
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
Daytime surface ozone distributions, 2006-2010
Spring SummerCooper et al. [2012]
Daytime surface ozone trends, 1990-2010
Spring SummerCooper et al. [2012]
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
Ozone trends in remote air at northern mid-latitudes
D.D. Parrish, NOAA
Rising surface ozone pollution in China
D.D. Parrish, NOAA
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