Transboundary influences on US background ozone
-
Upload
harlan-briggs -
Category
Documents
-
view
21 -
download
2
description
Transcript of Transboundary influences on US background ozone
Transboundary influences on US background ozone
Huiqun Wang1 ([email protected])Philippe Le Sager2 ([email protected])
Rokjin Park3 ([email protected])Daniel Jacob2 ([email protected])
1. Smithsonian Astrophysical Observatory2. Harvard University3. Seoul National University
Work sponsored by U.S. Department of Energy, Office of Fossil Energy, through a contract with Argonne National Laboratory
2
According to EPA, counties violating the current 80 ppb ozone standard are largely limited to southern California, the Northeast
coastal corridor, and isolated other parts of the eastern US
3
EPA further shows that lowering the standard to 75 ppb or 70 ppb would significantly increase the number of counties in violation,
based on current air quality data
4
Application of GEOS-Chem global air quality modelto quantify transboundary pollution influence
GEOS-Chem is a global model of ozone-PM chemistry using here NASA/GEOS assimilated meteorological data for 2001; horizontal resolution is 1o lat x 1o long (about 70x50 sq. mi.)
(1) Standard simulation; compare w/ observations to assess confidence in the model
(2) Set U.S. or N. American anthropogenic emissions to zero quantify U.S. background and North American background
(3) Difference between U.S. background and North American background Canadian+Mexican pollution enhancement (CANMEX)
(4) Set global anthropogenic emissions to zero quantify natural background
3-D model structure
5
Data from Fiore et al. [JGR, 2003b] for the period Mar-Oct 2001
Background ozone is important for setting the standard
Background is not directly measurableand needs to be estimated from models
CASTNet sites observations
GEOS-Chem at CASTNet
NA backgroundfrom GEOS-Chem
Natural backgroundfrom GEOS-Chem
NA backgroundfrom MOZART-2
6
NA background – no anthropogenic emissions in North AmericaUS background – no anthropogenic emissions in the US
AnthropogenicNOx Emissions World
NorthAmerica
USA Canada Mexico
(Tg N/Year) 25.4 8.1 6.7 0.5 0.9
The national totals of CAN and MEX are small, but there arenon-negligible emission sources close to the border
7
NA background (without NA anthropogenic emissions)
US background (without US anthropogenic emissions)
JJA
200
1 m
ean
, b
ased
on
dai
ly-8
h-m
ax
8
Canadian and Mexican influences (ppb)(JJA mean, based on daily-8h-max)
Enhancement to NA background is foundIn the Northeast and Southwest US
Selected rural measurement sites under CANMEX influences, avoiding mountain-top sites and sites with complex topography, traffic influence, and missing data
9
Canadian enhancement in the Northeast (ppb)(JJA mean, based on daily-8h-max)
The largest mean Canadian enhancement is 8.8 ppb(among all US grid boxes)
• Rural sites under CAN influence
10The largest mean Mexican enhancement is 13.1 ppb(among all US grid boxes)
• Rural sites under MEX influence
Mexican enhancement in the Southwest (ppb)(JJA mean, based on daily-8h-max)
11
BuffaloWestfield
Williamson
Kane Exp Forest
Unionville
Lykens
CAN enhancement at selected sites in the Northeastclose to Canadian sources
Daily-8h-max time series for these six locations follow …
12
Measurement Std-run US-background NA-background CANMEX
The largest episodic CAN enhancement at Unionville, MI (34 ppb) increases US background to 47 ppb (red circle)
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
13
Measurement Std-run US-background NA-background CANMEX
Westfield, NY
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
14
Measurement Std-run US-background NA-background CANMEX
Williamson, NY
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
15
Measurement Std-run US-background NA-background CANMEX
Kane Exp Forest, PA
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
16
Measurement Std-run US-background NA-background CANMEX
Lykens, OH
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
17
Measurement Std-run US-background NA-background CANMEX
Buffalo, NY: At Buffalo, the CAN influence is frequently above 10 ppb, and US background is frequently above 30 ppb
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
18
2010 CAIR: Source Apportionment: Buffalo Average Contribution by State/Sector to Exceedance-level Ozone
Canada-NR28%
Canada-NEGU14%
Canada-MV11%
Other-NR10%
Other-MV9%
Other-EGU7%
Other-NEGU5%
NY-NR3%
Other-ST3%
NY-MV3%
NY-ST1%
NY-EGU1%
NY-NEGU0%
Nearby-MV0%
Canada-EGU0%
Nearby-NR0%
Nearby-NEGU0%
Canada-ST6%
Percentage Contribution by State: Buffalo nonattainment area
0
10
20
30
40
50
60
70
CN NY WI MI KS IL IA MO
Percentage Contribution by Sector:Buffalo nonattainment area
0
10
20
30
40
50
Non-RoadMobile (NR)
On-RoadMobile(MV)
Non-EGUPoint
(NEGU)
StationaryArea (ST)
EGU Point(EGU)
AverageFires (AV)
For Buffalo, EPA has shown that Canadian sources contribute 59% to ozone precursors on peak ozone days
(Slide from EPA presentation)
19
BuffaloWestfield
Williamson
Kane Exp Forest
Unionville
Lykens
Greenbelt
Stow
Wash. Crossing
High episodic CAN contributions are experienced as far south and east as Eastern MA, New Jersey, and the Washington DC area
Daily-8h-max time series for these more distant locations follow …
20
Measurement Std-run US-background NA-background CANMEX
Stow, MA
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
21
Measurement Std-run US-background NA-background CANMEX
Washington Crossing, NJ
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
22
Measurement Std-run US-background NA-background CANMEX
Greenbelt, MD
Inverted black triangles show days in which CAN enhancement is >10 ppb and observed ozone concentration is >80 ppb
23
Measurement Std-run US-background NA-background CANMEX
Alpine, CA: The situation in the Southwest is different from the Northeast; there is a larger mean enhancement but fewer sharp
episodes. MEX influence is frequently above 10 ppb, and US background is frequently above 30 ppb
Inverted black triangles show days in which MEX enhancement is >10 ppb and observed ozone concentration is >80 ppb
24
Canadian influence is >10 ppb on some peak ozone days (>80 ppb) Canadian influence is always <10 ppb on peak ozone days (>80 ppb) Untagged color boxes have max surface ozone <= 80 ppb
Max CAN contribution on peak ozone days is 23 ppb among boxes shown as: ■
CAN influence is important for areas near the Great Lakes and the Northeast coast
25
Canadian influence is >10 ppb on some peak ozone days (>75 ppb) Canadian influence is always <10 ppb on peak ozone days (>75 ppb) Untagged color boxes have max surface ozone <= 75 ppb
26
Note that as the reference ozone value is decreased, increasingly larger areas of the Southeast and industrial Midwest are influenced
Canadian influence is >10 ppb on some peak ozone days (>70 ppb) Canadian influence is always <10 ppb on peak ozone days (>70 ppb) Untagged color boxes have max surface ozone <= 70 ppb
27
Canadian influence is >5 ppb on some peak ozone days (>80 ppb) Canadian influence is always <5 ppb on peak ozone days (>80 ppb) Untagged color boxes have max surface ozone <= 80 ppb
28
Canadian influence is >5 ppb on some peak ozone days (>75 ppb) Canadian influence is always <5 ppb on peak ozone days (>75 ppb) Untagged color boxes have max surface ozone <= 75 ppb
29
Canadian influence is >5 ppb on some peak ozone days (>70 ppb) Canadian influence is always <5 ppb on peak ozone days (>70 ppb) Untagged color boxes have max surface ozone <= 70 ppb
At CAN = >5 ppb and ozone = >70 ppb, much of the eastern US is influenced, even into North Carolina
30
70 75
2850
280
93
527
85416792936
Contribution of CAN pollution to exceedances of different levels of ozone concentration (I)
Includes all US grid boxes within [36N-48N, 88W-66W] (15,180 data points)
Y:
X:
138
Number of data points exceeding specified values of CAN enhancement and ozone concentration (cumulative)
En\Oz >70 ppb >75 ppb >80 ppb
>10 ppb 3.2% 3.0% 3.3%
>5 ppb 17.9% 16.7% 16.2%
30
31
Scatter plot based on timeseries at the gridboxes withOzone > 80ppb and Canadian influence > 5ppb
284371
138
540
225
916
359
1409
Sorted to include only the 56 grid boxes that had at least one case of X >80 ppb and Y >5 ppb, i.e., under some Canadian influence (5,152 data points)
En\Oz >70 ppb >75 ppb >80 ppb
>10 ppb 5.0% 4.7% 5.2%
>5 ppb 25.5% 24.6% 25.6%
Number of data points exceeding specified values of CAN enhancement and ozone concentration (cumulative)
Contribution of CAN pollution to exceedances of different levels of ozone concentration (II)
31
32
Mexican influence is >10 ppb on some peak ozone days (>80 ppb) Mexican influence is always <10 ppb on peak ozone days (>80 ppb) Untagged color boxes have max surface ozone <= 80 ppb
Max MEX contribution on peak ozone days is 18 ppb among boxes shown as: ■
MEX influence is important for southern California and parts of Arizona and Texas
33
Mexican influence is >10 ppb on some peak ozone days (>75 ppb) Mexican influence is always <10 ppb on peak ozone days (>75 ppb) Untagged color boxes have max surface ozone <= 75 ppb
34
Mexican influence is >10 ppb on some peak ozone days (>70 ppb) Mexican influence is always <10 ppb on peak ozone days (>70 ppb) Untagged color boxes have max surface ozone <= 70 ppb
35
Mexican influence is >5 ppb on some peak ozone days (>80 ppb) Mexican influence is always <5 ppb on peak ozone days (>80 ppb) Untagged color boxes have max surface ozone <= 80 ppb
36
Mexican influence is >5 ppb on some peak ozone days (>75 ppb) Mexican influence is always <5 ppb on peak ozone days (>75 ppb) Untagged color boxes have max surface ozone <= 75 ppb
37
Mexican influence is >5 ppb on some peak ozone days (>70 ppb) Mexican influence is always <5 ppb on peak ozone days (>70 ppb) Untagged color boxes have max surface ozone <= 70 ppb
At MEX = >5 ppb and ozone = >70 ppb, MEX influence extends into Nevada, New Mexico, and NW Texas
38
142853
49109271
41310022453
70 75
Contribution of MEX pollution to exceedances of different levels of ozone concentration (I)Y
:
X:
Includes all US grid boxes within [26N-42N, 120W-90W] (34,960 data points)
Number of data points exceeding specified values of MEX enhancement and ozone concentration (cumulative)
En\Oz >70 ppb >75 ppb >80 ppb
>10 ppb 2.2% 2.8% 3.4%
>5 ppb 11.0% 10.9% 11.9%
38
39
Scatterplot based on timeseries at gridboxes with Ozone > 80 ppb & Mexican enhancement > 5 ppb
14
49
125
27
90
223
43
155
379
En\Oz >70 ppb >75 ppb >80 ppb
>10 ppb 11.3% 12.1% 11.2%
>5 ppb 40.9% 40.4% 39.2%
Number of data points exceeding specified values of MEX enhancement and ozone concentration (cumulative)
Contribution of MEX pollution to exceedances of different levels of ozone concentration (II)
Sorted to include only the 15 grid boxes that had at least one case of X >80 ppb and Y >5 ppb, i.e., under some Mexican influence (1,380 data points)
39
40
CONCLUSIONS• Transboundary pollution from Canada and Mexico increases the mean background surface ozone
concentration in the US in JJA by 1-13 ppb.
• The largest Canadian enhancement is 8.8 ppb (JJA mean), with an episodic maximum of 34 ppb (at
Unionville, MI) in the daily-8h-max time series.
• The largest Mexican enhancement is higher, 13.1 ppb (JJA mean), but the maximum in the daily-8h-
max time series is smaller (21 ppb, not shown).
• For peak ozone cases, the US background can be >30 ppb and even 40 ppb due to transboundary
influences.
• Transboundary pollution can contribute significantly (up to 23 ppb in the Northeast and 18 ppb in
the Southwest) to peak ozone levels (in this case, defined as >80 ppb).
• Canadian contributions on peak days (>70, > 75, or > 80 ppb ozone) can exceed 10 ppb as far from
Canada as near Washington, DC; central New Jersey, and eastern Massachusetts; Mexican
contributions can be consistently higher in some cases, but focused on closer areas of S. California,
S. Nevada, and western to central Arizona.
• Cross-border contributions of these magnitudes impose significant penalties for some regions of the
country, i.e., in order to achieve a tightened ozone standard, parts of MI, NY, PA, and other
Northeastern and Midwestern locations would have to get substantial additional emission reductions,
depending on location, to offset the Canadian influence.