Chemical transport modeling in support of NPS-CIRA activities

Mike Barna1

Marco Rodriguez2

Kristi Gebhart1

Bret Schichtel1

Bill Malm1

Jenny Hand2

1 ARD-NPS, Fort Collins, CO2 CIRA, Fort Collins, CO

June 16, 2011National Park ServiceU.S. Department of the Interior Cooperative Institute

for Research in the Atmosphere

Air quality models, generally speaking

• Air quality models are ‘transfer functions’ that convert emissions to impacts (concentration & deposition) at downwind receptors

• They are useful for…• Filling in gaps of unmonitored species• Developing source apportionments• Evaluating ‘what if’ scenarios• A component in a weight-of-evidence evaluation

• Want to employ current ‘state-of-the-science’ models in our work

Models used for regulatory work

puff models

near-fieldmodels

oneatmosphere

models

e.g., AERMOD

What are the peak exposure levels very

near a source?

e.g., Calpuff

What are the impacts from this powerplant

plume?

e.g., CAMx

What is the chemical state of the

atmosphere, and which sources influenced it?

complexity

How CAMx works

• CAMx treats the atmosphere as a big box (the ‘model domain’) which is then chopped-up into a bunch of little boxes.

• In each little box, the chemical evolution over time is evaluated, and once per hour the concentration and deposition of species is reported.

Things that CAMx can do (or try to do)

• Sulfate• Ozone• Oxidized nitrogen• Reduced nitrogen• Organics• Deposition• Wind blown dust• Toxics/mercury

easier

harder

Current modeling efforts

• Simulating oxidized and reduced nitrogen impacts at Rocky Mountain NP (RoMANS2)

• Examining the ‘carrying capacity’ of western US airsheds in terms of nitrogen deposition and ozone

• Air quality impacts from oil and gas development

• Fire impacts on regional ozone (DEASCO3)

Need a large-scale perspective

• Pollutants and precursors can travel 100’s – 1000’s kms before reaching a receptor

• Lots of things can happen en route:• Chemical transformation• Deposition

(Tong & Mauzerall, 2008)

The NPS – CIRA modelers

• Kristi Gebhart (NPS), Marco Rodriguez (CIRA), Mike Barna (NPS)

• Modeling hardware:• 30 Xeon cores• 60 GB memory• 50 TB storage

Two examples of current modeling

• Nitrogen deposition

• Ozone

Nitrogen deposition

11

• NH3: rapid deposition, NH3 NH4+, no gas-phase oxidation

• NOx: complicated photochemistry, HNO3 NO3-, some species rapidly deposit (HNO3, NO.)

NH3 NOx

Where does the nitrogen go?

12

CASTNet species:

example ‘missing N’ species:

Simulated nitrogen

13

NH4+

NO3

SO4=

NH3

HNO3

SO2

Beaver Meadows (RMNP) Grant, Nebraska

RoMANS CAMx results, April 2006

spring: summer:

Example CAMx apportionment (w/PSAT)

CAMx tracer runs

• Another apportionment tool is to treat emissions as conserved tracers, and then apply statistical models to indicate largest contributors

Estimated NH3 emissions in Brush, CO

Ozone

18(Jaffe & Ray, 2007)

Western ozone trends

Simulated 8hr ozone (2005)

Observed peak 8hr ozone (2004 – 2006)

(WRAP, 2010)

21

NOx emissions from O&G

22

Ozone impacts from oil & gas emissions

Ozone impacts from NGS NOx

 National Park  Peak hourly ozone impactfrom NGS (ppb)

Grand Canyon (Marble Canyon) 15Grand Canyon (Grand Canyon Village) 6Canyonlands 3Capitol Reef 7Bryce Canyon 5Zion 3Mesa Verde 2

Should we focus on VOCs or NOx?

HCHO

NO2

HCHO/NO2

HCHO and NO2 can be detected from the OMI satellite, and provide

‘indicator species’ to help assess whether a region is

VOC or NOx limited.

HCHO/NO2 > 1Suggests NOx limited

(Duncan et al., 2010)

Summary

• Established modeling group working on issues important to NPS, including nitrogen deposition and ozone

• It’s notable that several of our projects are linked to nitrogen emissions

• Future projects:• Climate change influence on regional air quality• Fire impacts