a ttaining the new US ozone NAAQS Panel on Meeting the New Ozone Standard Energy Summit 2015 University of Wisconsin Madison WI October 13 2015 Arlene M Fiore Acknowledgments ID: 553617
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Slide1
A regional-to-global perspective on
attaining the new U.S. ozone NAAQS
Panel on Meeting the New Ozone Standard
Energy Summit 2015University of Wisconsin, Madison, WIOctober 13, 2015
Arlene M. Fiore
Acknowledgments: George Milly, Lukas Valin (LDEO)Harald Rieder (U Graz, Austria)Lok Lamsal (NASA GSFC)
83520601 Slide2
Ground-level O
3 is produced photochemically in the atmosphere, from both natural and anthropogenic sourcesO
3
+
CH
4
NMVOC
NO
x
Fuel local-to-regional ozone
pollution episodes
Raises background ozone levels
Observed surface ozone includes background plus any ozone produced from local-to-regional emissionsSlide3
1950s
Present
1980s
NMVOCs
+ NO
x
+ CH
4
??
U.S. o
zone abatement strategies evolve with our understanding of the O
3 problem
Abatement
Strategy:
O
3
smog recognized
as an URBAN problem:
Los Angeles,
Haagen-Smit identifies
chemical mechanism
Smog considered
REGIONAL problem;
role of biogenic
VOCs discovered
A GLOBAL perspective:
role of intercontinental
transport, background
Slide4
Lower O3 NAAQS level likely expands non-attainment regions
Cooper et al., Science, 20152011-2013 ozone design values at EPA approved ozone monitoring sitesSlide5
Cleaner U.S. air is visible from spaceSatellite (OMI) tropospheric NO
2 columns c/o Lok Lamsal
& Bryan Duncan, NASA GSFCNew OMI NO2 website:
airquality.gsfc.nasa.govSlide6
Tropospheric column NO2 higher on weekdays vs. weekends, mainly attributable to weekly cycle in diesel NOx emissions
WEEKEND WEEKDAY
Mid-2000s
Following NOx emission controls, current weekday tropospheric NO2 columns look more like past weekends
Early 2010s
Luke
ValinLDEO,in prep.Slide7
Similar patterns occur in surface ozone90th% summer afternoon surface ozone (U.S. EPA AQS)
Additional diesel NOx controls would lower weekday surface ozone (and tropospheric NO2 columns) Implies regional
NOx-sensitive ozone production
WEEKDAYWEEKENDLuke ValinLDEO,in prep.
Mid-
2000s
Early
2010sSlide8
2001
-2005
2021
-2025(RCP8.5)
# DAYS
OBSERVED
OBSERVED + MODELED
Future projections in the context of the revised O
3
NAAQS
Number of summer (JJA) days with MDA8 O3
> 70 ppb at CASTNet sitesAPPROACH1. Use chemistry-
climate model (GFDL CM3) to estimate regional-scale changes2. Apply modeled changes at each percentile to observed distribution at each site
Rieder
et al., in prep, 2015
40% decrease in EUS
NO
x
emissions over near-term (2020-2005) leads to 3 or fewer summer days with MDA8 O
3
> 70 ppb
at all but 5 sites
?Slide9
Future projections in the context of the revised O3 NAAQS: a monitoring site in Dodge County, WI
2001-2005OBSERVED
2021-2025OBSERVED + MODEL (RCP8.5) REGIONAL CHANGES AT EACH PERCENTILE
Moving from 75 to 70 ppb doubles # days > NAAQS levelProjected regional-scale O3 decreases suggest near-term attainment of new standard possibleH. RiederSlide10
The “tightening vise”
of ozone management
Ozone concentration
Historical
Future
(alternate view)
Hemispheric
background
Regional
Local
Standard
Future
Keating, T. J., J. J. West, and A. Farrell (2004) Prospects for international management of intercontinental air pollutant transport, in A.
Stohl
, Ed.,
Intercontinental Transport of Air Pollution
, Springer, p. 295-320.
Future may require concerted efforts to lower backgroundSlide11
Reducing methane lowers hemispheric background
ozone (plus climate co-benefit)
~ 1 ppb
across the northern hemisphere
[Fiore et al., JGR, 2009; TF HTAP, 2007, 2010; Wild et al., ACP, 2012]
7700-400,000 annual avoided cardiopulmonary
premature mortalities in the N.
H
emisphere uncertainty in concentration-response relationship only
[Casper Anenberg
et al., ES&T, 2009]
Range
over
18 models
Global
mean
a
voided warming
in
2050 (
°C
)
[WMO/UNEP, 2011]
CLIMATE
OZONE AIR QUALITY
Benefits of ~25% decrease in global
anthropogenic methane
emissions
North
America
Europe
East
Asia
South
AsiaSlide12
E
stimated in a model (GEOS-
Chem
) by turning off N. American anthropogenic emissions
Background over the U.S.A. is highest in the west
(at altitude) and in spring
Latest background estimates
(recent years,
higher resolution) support general conclusions; emphasis now on episodic background events
e.g., Wu et al., 2008; Wang et al., 2009; McDonald-
Bueller
et al. 2011; Mueller & Mallard, 2011; Zhang et al., 2011; 2014; Emery et al., 2012; Lin et al., 2012ab; Fiore et al.,
AtmEnv, 2014
Summer 1995 afternoon average background ozone
[Fiore et al., JGR, 2002]
12
20
28
37
Ozone (ppb)
[Fiore et al., JGR,
2003]
Monthly afternoon mean ozone
o
ver the Northeast U.S.A., 2001
J F M A M J J A S O N D
Month of 2001
Ozone (ppb)
OBS.
Model
BackgroundSlide13
Setting achievable standards requires accurate knowledge of background levels
120 ppb 1979
1-hr avg
84 ppb1997 8-hr
75
ppb 2008 8-hr
40
60
80
100
120
O
3
(
ppbv
)
20
U.S. National Ambient Air Quality Standard
for O
3
has evolved over time
typical
average
U.S. “
background”
(model estimates)
[
Fiore et al., 2003;
Wang et al., 2009;
Zhang et al., 2011]
“Allowable”
O
3
produced from U.S. anthrop. sources (“cushion”)
Lowering U.S
. O
3
NAAQS
levels implies
thinning
cushion
between regionally produced O
3
and background
background
events over WUS
[e.g., Lin et al., 2012ab]
70
ppb
2015
8-hr
Adapted from D.J. Jacob & NAS, 2009 Slide14
An Air Quality Management Challenge: NATURAL EVENTS How to detect and attribute accurately?
Fiore et al., EM 2014 (NASA AQAST special issue)
Examples of how
satellite, in situ measurements and models can be combined to detect and attribute exceptional eventsWILDFIRES
STRATOSPHERICINTRUSIONSSlide15
Downward ozone trend as EUS
NO
x
emission controls are implementedDecreasing NOx emissions reduces sensitivity of O
3 to temperature; continued controls should guard against climate-driven increases
[e.g., Bloomer et al., 2009; Rasmussen et al., 2012; Brown-Steiner et al., 2015]Observations at U.S. EPA CASTNet site Penn State, PA 41N, 78W, 378mJuly mean MDA8 O3 and July mean daily maximum temperature
An Air Quality Management Challenge: CLIMATE CHANGEWill warmer temperatures worsen O3 pollution?
G.
Milly
Figure 6a of Fiore, Naik
, Leibensperger
, JAWMA, 2015Slide16
Attaining the new U.S. ozone NAAQS: A regional-to-global perspectiveContinued
regional NOx decreases should facilitate attainment with new standard (NOx-sensitive ozone production) over the eastern U.S.A.Background contributions to U.S. surface ozone vary in space and timeExceptional events may become more common with respect to a tighter standard and under climate change (e.g., wildfires)Trans-boundary transport could increase if foreign emissions rise (see next panel) Methane emission reductions would lower hemispheric background ozone levels (and also decrease climate forcing)