Transcript U.S. EPA’s Models-3 : An Integrated “One

Multi-Scale Applications of U.S. EPA’s
Third-Generation Air Quality Modeling System
(Models-3/CMAQ)
Carey Jang, Pat Dolwick,
Norm Possiel, Brian Timin, Joe Tikvart
U.S. EPA
Office of Air Quality Planning
and Standards (OAQPS)
Research Triangle Park, NC , U.S.A.
OUTLINE

Models-3/CMAQ system
• One-Atmosphere perspective

Multi-Scale Applications of Models-3/CMAQ
• Western U.S. Application
• Annual Nationwide U.S. Application
• Eastern U.S. Application
• Hemispheric/Continental Modeling Initiative
Features of Models-3/CMAQ

“Open-Access” Community-Based Models :
• User-friendly, Modular, Common modeling framework for
scientists and policy-makers.

Advanced Computer Technologies :
• High performance hardware and software technologies
(Cross-platform, GUI, distributed computing, visualization
tools, etc.).
 “One-Atmosphere”
Modeling :
• Multi-pollutant (Ozone, PM, visibility, acid
deposition, air toxics, etc.), Multi-scale.
Regulating Air Pollution: One-Atmosphere Approach
Mobile
Sources
Ozone
NOx, VOC,
Toxics
PM
(Cars, trucks, airplanes,
boats, etc.)
Industrial
Sources Chemistry
Acid Rain
NOx, VOC,
SOx, Toxics
Visibility
(Power plants, factories,
refineries/chemical plants, etc.)
Area
Sources
NOx, VOC,
Toxics
(Homes, small business,
farming equipment, etc.)
Meteorology
Air Toxics
Atmospheric
Deposition
NOx-Related Air Quality Issues
(NO3-, NH4+)
(NOx + VOC + hv) -->
PM
Ozone
NOx
Acid Rain
Visibility
(NO3- deposition)
(Fine PM)
Water Quality
(Nitrogen deposition,
Lake Acidification)
SOx-Related Air Quality Issues
(Fine PM)
(SO42-, NH4+)
Visibility
PM
SOx
Acid Rain
Water Quality
(SO42- deposition)
(Lake acidification,
Toxics deposition)
.
OH role in pollutants formation : One-Atmosphere
PM2.5
VOC + OH --->
Orgainic PM
Fine PM Visibility
(Nitrate, Sulfate,
Organic PM)
Ozone
.
OH
NOx + VOC + OH
+ hv ---> O3
Acid Rain
Water
Quality
NOx + SOx + OH
(Lake Acidification,
Eutrophication)
SOx [or NOx] + NH3 + OH
---> (NH4)2SO4 [or NH4NO3]
SO2 + OH ---> H2SO4
NO2 + OH ---> HNO3
Air Toxics
OH <---> Air Toxics
(POPs, Hg(II), etc.)
Example of “One-Atmosphere” Modeling
Impact of
50 % NOx
Emission Reduction
on PM 2.5
Impact of 50% NOx emission reduction
Nitrate PM decrease
Sulfate PM decrease
Impact of 50% NOx emission reduction
O3 decrease
HOx decrease
Models-3/CMAQ Applications at OAQPS
Purpose: To evaluate Models-3/CMAQ
feasibility as a regulatory tool

Western U.S. Application
• New domain, episodic O3

Annual Nationwide U.S. Application
• Annual PM & visibility
Eastern U.S. Application
• Urban & SIP applications
Hemispheric/continental Modeling Initiative
• Linkage of climate change and air pollution


Western U.S. Application

Objectives :
• New M3/CMAQ Domain
• New Episode (July 1996)

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Model Setup :
•
•
•
•
•
Episodic O3 modeling
Meteorology : MM5
Emissions : Tier-2 regridded
36km/12km, 12 layers
Compare against observations and UAM-V
153
Annual Nationwide U.S. Application

Objectives :
• Annual CMAQ Run
• Nationwide CMAQ Domain

Model Setup :
•
•
•
•
•
Annual PM and O3 (1996)
36-km, 8 vertical layers
Meteorology : MM5
Emissions Processing: SMOKE
Model Evaluation: Compared against observed
data (IMPROVE & CASTNET) & REMSAD
Models-3/CMAQ Simulation: Annual Average
PM 2.5
Sulfate PM
Nitrate PM
Organic PM
National 1996 CMAQ Modeling:
O3 (July Max)
Visibility (1996 avg.)
National 1996 CMAQ Modeling (January average)
Sulfur Wet Deposition
Nitrogen Wet Deposition
CMAQ Sensitivity Studies

CB4 vs. RADM2
• Is RADM2 a better mechanism than CB4 for PM
modeling?
• Run CMAQ w/ both CB4 and RADM2 for January and
July, 1996

NH3 sensitivity
• Are NH3 emissions the culprit of nitrate PM overprediction?
• Run CMAQ w/ 50% reduction of NH3 emissions for
January and July, 1996

Boundary conditions sensitivity
• Run CMAQ w/ 10 ppb O3 increase along the western
boundary for January and July, 1996
PM 2.5 (January Avg.)
Original CB4
RADM2
PM_SO4 (Jan. Avg.)
Orig. CB4
RADM2
Fixed CB4
NH3 Sensitivity Modeling
Nitrate PM : (January Avg.)
Base
50% NH3 reduction
CMAQ Sensitivity : Boundary Conditions
Effect of a 10 ppb ozone increase
along the western boundary
Eastern U.S. Application

Objectives :
• SIP and urban applications
• Emission growth & control
• Nested MM5 runs

Features :
• O3 and PM, July 95
• OTAG-like 36/12-km domain,
nested with 4-km (NE, LM, AT, TX)
• SMOKE : Emissions processing
Climate Change/Air Pollution Modeling Initiative
Proposal :

Global and Regional
Modeling of
Ozone and PM
Goal :

Establish linkages
between climate
change and air
pollution
Climate Change/Air Pollution Modeling Initiative
Background :

O3 and PM are not only key air pollutants, but also major climateforcing substances;

Reduction of non-CO2 substances (e.g., O3 and PM, especially
black carbon) could be a viable alternative to CO2 reduction to
curb global warming. A key strategy suggested was to focus on
air pollution to benefit regional and local air quality and global
climate simultaneously (Hansen et al., PNAS, 2000);

Black carbon could be the second largest heating component after
CO2 contributing to global warming; Control of fossil-fuel black
carbon could be the most effective method of slowing glabal
warming (Jacobson, Nature, 2001);
Climate Change/Air Pollution Modeling Initiative
O3 (0.3+0.1)
Black (0.8)
Carbon
(Hansen et al., PNAS2001)
Climate Change/Air Pollution Modeling Initiative
Background (continued):

There is also mounting evidence that criteria pollutants originating from
some developing countries, especially those in Asia such as China and
India, could impact U.S. domestic air quality as well as contribute to the
global background of climate-forcing substances. This intercontinental
transport issue is expected to worsen with the rapid growth in emissions
in these regions.

For example, recent modeling studies showed that by 2020 Asian
emissions could contribute as much as 2 ~ 6 ppb of O3 in the western
U.S., offsetting the Clean Air Act efforts up to 25% in that region (Jacob et
al., Geophys. Res. Letts., 1999) and increase global mean O3 level up to
10% (Collins et al., Atmos. Env., 2000); Asian and Sahara dust could
contribute a significant amount of PM in the western and southeastern
U.S. (Husar, http://capita.wustl.edu/CAPITA/).
Climate Change/Air Pollution Modeling Initiative
M o d e ls -3 /C M A Q R u n E x a m p le
O z o n e (p p m ) 1 9 9 8 A p ril 1 1 : 1 2 0 0 U T C
(Byun and Uno, 2000)
Climate Change/Air Pollution Modeling Initiative
Objectives :



To evaluate available approaches for establishing the
linkages between air pollution and climate change and
enhancing modeling capacity within EPA to address
these linkage issues.
To explore the impacts of intercontinental transport of
O3 and PM as well as their implications for domestic
and regional air quality and global climate change
To design integrated emissions control strategies to
benefit global climate and regional and local air quality
simultaneously
Climate Change/Air Pollution Modeling Initiative
Work Plan :
Phase I : Short-Term (~6 months)

Establish a better scientific foundation in linking
climate change and air pollution by leveraging current
studies
1. Global Modeling of O3 and PM
2. Global Radiative Forcing of Aerosols
3. Emission Inventories for Climate-Forcing Pollutants

Develop a conceptual model and modeling protocol
under the guidance of an expert advisory panel
Climate Change/Air Pollution Modeling Initiative
Work Plan :
Phase II : Long-Term (1 ½~2 years)
Based on Phase I effort, a series of modeling efforts that will be conducted
to address the linkages between air pollution and climate change.
These efforts may include:
– Enhancement of modeling capability and emission inventories to better
represent the linkages to global air quality and climate.
– Development of nesting capability between global chemistry/climate
models and regional air quality models.
– Simulation of hemispheric or regional air quality under a variety of
scenarios about future global and regional emissions and air quality.
– Evaluation of global and regional air quality models using a diverse set
of observational data sets, including data from satellites, surface
networks, intensive field studies, etc.
– Assessment of the potential radiative forcing and climate benefits
resulting from planned and alternative non-CO2 control strategies
The End
Thank you