Impacts of changing U.S. - PowerPoint Presentation

Slide1

Impacts of changing U.S.

NOx emissions on ozone pollution: Insights from satellites, ground-based measurements and air quality models

ExxonMobil Research and Engineering

NOx Controls WorkshopBridgewater, NJJanuary 12, 2016

Arlene M. Fiore

83520601 Slide2

A

ttaining the U.S. National Ambient Air Quality Standards (NAAQS) for ozone remains a challengeMillions of people living in counties with air quality concentrations above the level of the U.S. National Ambient Air Quality Standards

One or more NAAQS

Ozone (8-hour)PM2.5 (annual/24-hr)PM10 (24-hr)

SO

2 (1-hr)

PM10

(24hr)

Lead (3-month)

NO

2 (annual/1-hr)

CO (8-hr)

0 20 40 60 80 100 120 140 160

2012

142.2

133.2

28.2

16.1

15.1

8.1

EPA, 2014: http

://

www.epa.gov

/

airtrends

/

aqtrends.html#comparisonSlide3

Today’s topics

Introduction to atmospheric chemistry of ozone formation and destructionInfluence of U.S. NOx controls on ozone air quality Overview of air quality modeling

Current research directions and challenges

-- Role of natural NOx sources-- Accuracy of emission inventories-- Source attribution for ozone (anthropogenic, biogenic, background components)-- Changing climateSlide4

Introduction to ozone pollution chemistrySlide5

Ground-level O

3 is produced photochemically in the atmosphere, from both natural and anthropogenic sources

O3

+

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 emissionsSlide6

Tropospheric O

3 formation & “Background” contributions

Continent

Fires

Land

Biosphere

(NMVOC,

NO

x

)

Human

activity

Ocean

stratosphere

lightning

“Background” ozone

Natural

sources

Continent

X

X

intercontinental

transport

OH

HO

2

VOC, CH

4

, CO

NO

NO

2

h

n

O

3Slide7

Regional average loss pathways for ozone in (polluted) U.S. boundary layer

Fiore et al., Journal of Geophysical Research, 2002Percentage (%) of total ozone (Ox

) lost via each pathway,estimated with the GEOS-Chem chemical transport model

for summer 1995deposition dominates O3 photolysis followed by OH production and O3 + HOx also important In high

NOx settings (urban, power plant plumes) O3 titration by NO also occursSlide8

Regional average loss pathways for ozone in (polluted) U.S. boundary layer

Based on Table 4 from Fiore et al., Journal of Geophysical Research, 2002Deposition dominates, with O3 photolysis followed by OH production and O

3 reaction with odd hydrogen radicals (OH, HO2) also important (relatively

moreso in humid eastern U.S.A.)In high NOx settings (urban, power plant plumes) O3 titration by NO also occurs

WESTERN U.S.A.EASTERN U.S.A.

Percentage (%) of total ozone (O

x) lost via each pathway,estimated with the GEOS-

Chem chemical transport model

for summer 1995Slide9

OZONE

CONCENTRATIONS vs.

NO

x AND VOC EMISSIONSAir pollution model calculation for a typical urban airshed

NO

x

-

saturated

NO

x

-limited

RidgeSlide10

Influence of U.S. NOx controls on ozone air quality Slide11

Cleaner U.S. air is visible from spaceSatellite (OMI) tropospheric NO

2 columns c/o Lok

Lamsal & Bryan Duncan, NASA GSFCNew OMI NO

2 website: airquality.gsfc.nasa.govSlide12

Consistent trends derived from satellite (OMI) vs. ground-based (AQS) measurements

c/o Bryan Duncan & Lok Lamsal, NASA GSFCSlide13

Satellite (OMI NO2) data indicate 20-40% decreases from 2005 to 2014 over most of the U.S.A.

c/o Bryan Duncan & Lok Lamsal, NASA GSFCSlide14

Trends in summer daytime (11am-4pm) 95% ozone at rural U.S. monitoring sites (

CASTNet): 1990 to 2010Cooper et al., JGR, 2012Decreases in EUS attributed in observations and models to NO

x emission controls [e.g., Frost et al., 2006

; Hudman et al., 2007; van der A. et al., 2008; Stavrakou et al., 2008; Bloomer et al., 2009, 2010; Fang et al., 2010]

significant

n

ot

significantSlide15

Extreme value theory methods enable

derivation of “return levels” for JJA MDA8 O

3 within a given time period (from GPD fit)

CASTNet site: Penn Station, PAReturn level = Probability of observing a value x (level) within a time window T (period)

Rieder

et al., ERL 2013

1988-

1998

1999-2009

Sharp decline in return levels

between early and later periods (NOx

SIP call)Consistent with prior work [

e.g., Frost et al., 2006; Bloomer et al., 2009, 2010]

Translates air pollution changes into

probabilistic language

Apply methods to all EUS

CASTNet

sites to derive

1-year and 5-year return levelsSlide16

Highest ozone events decrease over EUS following

NOx emission controlsRieder et al., ERL 2013

1988-1998

1999-2009

1-yr return level decreases by 2-16

ppb

1

-year levels remain above the NAAQS

ozone level (70 ppb) across much of EUS

1-year Return Levels for Summertime MDA8 Ozone Slide17

Can we exploit weekday-weekend patterns in NOx emissions (e.g., diesel) to assess impact of NOx reductions on ozone?

WEEKEND WEEKDAY

Mid-2000s

NO2 columns decline on weekends; following NOx controls, weekday tropospheric NO2 columns look like past weekends

Early 2010s

Luke

Valin

LDEO, in prep.

Satellite (OMI)

Tropospheric

NO

2

columnsSlide18

Similar patterns occur in surface ozone

90th% summer afternoon surface ozone (U.S. EPA AQS) Additional diesel NOx controls would lower weekday surface ozone (and tropospheric NO

2 columns) Implies regional

NOx-sensitive ozone productionWEEKDAYWEEKENDLuke ValinLDEO,in prep.

Mid-

2000s

Early

2010sSlide19

What is an air quality model?See accompanying animation

c/o Lee Murray (LDEO/NASA GISS)Slide20

Anthropogenic Emissions

(LADCO)

Biogenic Emissions

(LADCO)Meteorology(WRF)

Boundary Conditions(MOZART)

Dispersion,

Advection

Gas-phase chemistry

Aerosol Thermodynamics

Cloud- Aqueous Processes

Other Processes

CMAQ

Overview

c/o Alex

Karambelas

, U Wisconsin-MadisonSlide21

Current research directions and ongoing challenges Slide22

Natural vs. anthropogenic sources: Nitrogen oxides (NOx)

NOx = NO + NO2

(Precursor to tropospheric O

3)Relative importance varies by day, season, year!Slide23

Summertime NOx Sources over Contiguous U.S.A.

Estimates from Table 1 of Hudman et al., J. Geophys Res. Atmos., 2004 for July 1 – August 15 2004 Slide24

Uncertainties exist in the sectoral breakdown of U.S. anthropogenic NOx

NOy (NOx + oxidation products) too high, as is NO

y/CO Power plant

NOx is well known (CEMS) Implies mobile sources are overestimated (by >50%) in the most recent U.S. EPA inventory (NEI2011)observed

Modeled (CMAQ) using U.S. EPA NEI2011 inventory

Anderson et al., Atmos. Environ., 2014

Figure c/o Russ Dickerson (U MD)Slide25

How important are ‘natural’ NOx sources?

Soil NOx

Hudman et al., Atmos. Chem. Phys., 2010

Lightning and soil NOx vary daily, seasonally, and inter-annually. Their impacts on ozone are not well quantified, but are typically smaller than those from U.S. anthropogenic NOxModel estimates of soil and lightning NOx

influence on monthly mean maximum daily 8-hour (MDA8) average surface ozone June 2005-2008

June 2006

July 2004

Lightning NO

x[ppbv]

Fang et al., J.

Geophys. Res., 2010 Slide26

Wildfires are a ‘hot’ topic: How much ozone do they produce?Fiore et al., EM 2014 (NASA AQAST special issue;

Figures c/o R. Dickerson (U MD) excerpted from Taubman et al., 2004; Colarco et al., 2004)

Example (July 7-8 2002)of how satellite, in situ measurements and models can be combined to detect and attribute exceptional events

Ongoing research strives to understand the impact of fire effluents on high ozone levels Slide27

An air quality mgmt challenge: SOURCE ATTRIBUTIONHow much is transported? Background? International?

GEOS-Chem model “zero-out” simulations: one day during 2012 EUS heat wave Slide28

New insights into mid-latitude pollution expected from instruments aboard geostationary platforms with hourly, continuous coverage (~2018-2020 launch dates)

c/o Kelly Chance, Harvard SAO, AQAST7 Meeting, June 2014 Slide29

Co-variance between ozone and temperature implies that climate warming will degrade air quality in polluted regions

(well

established, e.g. see Jacob & Winner Atmos. Environ. review, 2009) Downward ozone trend as EUS NOx emission controls are implemented

Observations at U.S. EPA

CASTNet site Penn State, PA 41N, 78W, 378m

July mean MDA8 O

3 and

July mean daily maximum temperature An Air Quality Management Challenge: CLIMATE CHANGEWill warmer temperatures worsen O

3 pollution?

G.

Milly

Figure 6a of Fiore,

Naik

,

Leibensperger

, JAWMA, 2015Slide30

Decreasing NOx emissions reduces sensitivity of O3 to temperature; helps to guard against any “climate penalty”

[e.g., Bloomer et al., 2009; Rasmussen et al., 2012; Brown-Steiner et al., 2015]1988-2001: 4.1 ppb/C

2002-2014: 2.4 ppb/C

July mean MDA8 ozone (ppb)July mean maximum daily temperature (°C) G. MillyFigure 6b of Fiore, Naik

, Leibensperger, JAWMA, 2015Slide31

Our Team at Lamont-Doherty Earth Observatory of Columbia University

Arlene Fiore (PI)

GusCorrea

George MillyXiaomengJinLuke Valin(now @ EPA)

Lee MurrayOlivia

Clifton

Jean Guo

DanWestervelt

NoraMascioli

Not

shown but contributed to NASA AQAST projects: Yuxing Ma (CU, Masters), Cynthia Zucker

(Barnard ugrad), Melissa

Seto (CU ugrad), Jacob

Oberman

(U WI

ugrad

)