Implementation of the Particle & Precursor Tagging Methodology (PPTM) for the CMAQ Modeling System: Sulfur

& Nitrogen Tagging5th Annual CMAS Conference

Friday Center, UNC-Chapel Hill, NC17 October 2006

Tom Myers, Sharon Douglas & Jay HaneyICF International, San Rafael, CA

Presentation Outline

Conceptual overview of PPTM

Implementation of PPTM for sulfur and nitrogen in the CMAQ model

Testing & example results

S tagging application for pulp & paper sector

Overview of PPTM: Concepts

Emissions (or initial/boundary condition) species are tagged in the emissions (or IC/BC) files and continuously tracked throughout the simulation

Tags can be applied to source regions, source categories, individual sources, initial conditions, and/or boundary conditions

PPTM quantifies the contribution of tagged sources to simulated species concentrations & deposition

Base simulation results not affected by tagging

Overview of PPTM: Concepts

Within the model, tagging is accomplished by the addition of duplicate species (e.g., SO2_t1, SO2_t2)

Tagged species have the same properties and are subjected to the same processes (e.g., advection, chemical transformation, deposition) as the actual species

Mercury (Hg), sulfur (S), and nitrogen (N) tagging completed; tagging for elemental carbon (EC) and organic carbon (OC) under development/testing

Example Uses of PPTM for Sulfur and Nitrogen

Determine the contribution of SO2 emissions from an individual source, group of sources, or source category (e.g., electric generating units (EGUs), pulp and paper facilities) to sulfate and overall PM2.5 concentrations

Quantify/compare the contribution of NOx emissions from transportation sources, area sources (e.g., wood burning stoves) & offroad sources (e.g., IC engines, construction equipment) 

Implementation of PPTM for CMAQ: Sulfur & Nitrogen

CMAQ version 4.5

Tagged S elements include: SO2, ASO4I, ASO4J, SULF (for internal tracking)

Tagged N species include: ANH4I, ANH4J, ANO3I, ANO3J, NO, NO2, NO3,

N2O5, HNO3, HONO, PNA, PAN, NTR, NH3

Implementation of PPTM for CMAQ: Sulfur & Nitrogen

Key considerations/assumptions: Linear processes simulated directly Potentially non-linear processes calculated

for total species and apportioned to tags Additional terms from some processes

saved to ensure proper allocation Gas-phase chemistry routines have

additional production & loss terms added; NO, NO2, NO3, N2O5 changes apportioned based on NOx totals for each tag

Implementation of PPTM for CMAQ: Sulfur & Nitrogen

Key considerations/assumptions: Other N species calculated with

additional chemistry terms; adjusted so net production/loss for sum of tags matches that for the whole

Simulation calculates the overall species value as the sum of all tags; tags must be defined to add up to the whole

Implementation of PPTM for CMAQ: Sulfur & Nitrogen

CPU requirements increased by approximately 15% for 3 S tags and 50% for 3 N tags

Documentation/user’s guide available from EPA or ICF as follows:

Douglas, S., T. Myers and Y. Wei. 2006. “ Implementation of

Sulfur and Nitrogen Tagging in the Community Multiscale Air Quality (CMAQ) Model.” Prepared for EPA, OAQPS, Research Triangle Park, NC. ICF International, San Rafael, California (06-076).

Example Sulfur Tagging Results

CMAQ PPTM: Contribution to Monthly Average Sulfate

CMAQ PPTM: Contribution to Monthly Average Sulfate

CMAQ PPTM: Contribution to Monthly Average Sulfate

0

0.05

0.1

0.15

0.2

Great Smoky Mountains

Facility_1 Facility_2 Facility_3

CMAQ PPTM: Site-specific SO4 Contributions (IMPROVE Sites)

ugm

-3

CMAQ simulated monthly average contribution to sulfate from three example EGU facilities.

Sulfur Tagging Application for the Pulp & Paper Sector

Based on CAIR 2010 modeling & emission inventory

1 month simulation period (July)(Annual simulation ongoing)

Tags applied for 10 pulp & paper sources and IC/BCs

CMAQ PPTM: Monthly Average Sulfate for July 2010

CMAQ PPTM: Contribution to Monthly Average Sulfate

CMAQ PPTM: Contribution to Monthly Average Sulfate

0

0.05

0.1

0.15

0.2

Great Smoky Mountains

Tag 1 Tag 2 Tag 3 Tag 4 Tag 5Tag 6 Tag 7 Tag 8 Tag 9 Tag 10

CMAQ PPTM: Site-specific SO4 Contributions (IMPROVE Sites)

ugm

-3

CMAQ simulated monthly average contribution to sulfate from regional pulp & paper facilities.

0

0.1

0.2

0.3

0.4

Chattanooga

Tag 1 Tag 2 Tag 3 Tag 4 Tag 5Tag 6 Tag 7 Tag 8 Tag 9 Tag 10

CMAQ PPTM: Site-specific SO4 Contributions (Urban Sites)

ugm

-3

CMAQ simulated monthly average contribution to sulfate from regional pulp & paper facilities.

0

0.05

0.1

0.15

0.2

Cincinnati

Tag 1 Tag 2 Tag 3 Tag 4 Tag 5Tag 6 Tag 7 Tag 8 Tag 9 Tag 10

CMAQ PPTM: Site-specific SO4 Contributions (Urban Sites)

ugm

-3

CMAQ simulated monthly average contribution to sulfate from regional pulp & paper facilities.

Example Nitrogen Tagging Results

0

1

2

3

4

5

6

ugm

-3 (

x 1

0-2

)

EGU Non-EGU Other Total Base Diff

-2

0

2

4

6

8

10

12

14

ppm

(x 1

0-4

)

EGU Non-EGU Other Total Base Diff

Example CMAQ PPTM Nitrogen Tagging Results: Great Smoky

Mtns

0

2

4

6

8

10

ugm

-3 (

x 1

0-1

)

EGU Non-EGU Other Total Base Diff

NH4

NO3

NOx

EGU

Non-EGU

Other

Example CMAQ PPTM Nitrogen Tagging Results: Great Smoky

MtnsNH4

NO3

NOx

Summary of CMAQ PPTM Status and Next Steps

PPTM has been successfully implemented in the CMAQ model for S, N (and Hg) and quantifies the contribution of tagged sources to simulated PM

Application & interpretation of results is straightforward (no hidden assumptions)

Initial test results indicate that numerical effects (uncertainties) are small, compared to contribution estimates

Next steps include Complete implementation for OC & EC Add OPTM (for ozone)