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WAQS Source Apportionment Modeling Update

Ralph MorrisIWDW/WAQS Technical Committee

January 12, 2016Fort Collins, Colorado

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Content: Source Apportionment (SA)

• Overview of WAQS Source Apportionment Plan– Round 1 – Geographic (done)– Round 2 – Source Sector (done)– Web-based SA Visualization Tool (in progress)– Round 3 – Detailed 4 km SA (not started)

• Preliminary Results (Round 1) • Visualization Tool Status (Update)• Updates to CAMx SA Tool (information)• Potential Approaches for Round 3 (feedback)

R1: Geographic Source Apportionment

• 2011a Emissions• 21 Source Regions• 5 Source Categories

– Natural (Bio, Lx, SS, WBD)– 3 Fires (WF, Rx, Ag)– Remainder Anthropogenic

• Ozone/APCA 36/12 km• PSAT/PM 36 km • O3, PM, Vis and Dep Contribution• CSAPR-type Analysis• RHR Impaired vs. W20% Days

R2: Source Sector Apportionment• 2011b Emissions• Source Categories:

– Natural (Bio, LNOx, SS, WBD)

– Wildfires (WF)– Rx+Ag Fires– O&G– EGU Point– Other Point– On-Road– Non-Road– Remainder Anthro

• Five Source Regions– CO, UT, WY and NM– Remainder

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R3: Detailed 4 km SA• Examine local source

contributions in more detail, possibilities: – Episodic period(s) from

2011– State subregions– Source subcategories

• Will discuss in more detail at end of this PPT– Request feedback from

Technical Committee

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R1 Results: CASPR-Type Analysis• Run Model Attainment Test Software (MATS) using

CAMx base output and output from each State’s anthropogenic emissions removed– Anthro = Anthropogenic + Rx and Ag fires– Provides State’s contribution to Design Values

• 8-Hour Ozone and 24-Hour and Annual PM2.5

• CASPR-type analysis– User selects level of NAAQS and Upwind State– Spread sheet performs analysis summarizing Downwind

States where the Upwind State contributes significantly• Significance defined as 1% of the NAAQS

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Drop Down Menu for Upwind State and Level of NAAQS

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Downwind States where the Upwind State (CO) Contributes Significantly to Ozone Nonattainment in a

Downwind State under 70 ppb Ozone NAAQS

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Source Contributions at Downwind States

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Web-Based SA Visualization Tool

• Received comments on Prototype that was based on 2008 WestJumpAQMS top highest modeled 8-hour ozone days– Biggest comment was to extract SA information at more

locations than just the monitoring networks– Added virtual gridded network covering western U.S. at 36

km resolution• Updated SA Vis Tool with WAQS R1 Geographic ozone

SA results for every day of year

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WAQS Receptors for Data Extraction

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Ozone PM

Ozone Vis Tool Opening Page

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Site Selection: Dropdown or MapDay Selection: Dropdown or Calendar

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AQS Network Locations

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Map Browser

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Day Selection

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Add Time Series SA Capability

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Updates to CAMx Source Apportionment Tool

OSAT – apportion ozone changes (ΔO3) to tracers O3N and O3VAPCA – only assign O3 formed to biogenic when due to interactions of biogenic VOC and biogenic NOX (policy relevant)“OSAT2” – simultaneously treat O3 production and destruction“OSAT3” – treat odd oxygen in NO2 and NOX recycling

Improve OSAT algorithms

Track odd-oxygen through NO2

– When NO2 accumulates, e.g., overnight in urban cores

– Requires NO2 apportionment

Track NOX recycling

– Source of NOX where emissions are low

– Apportion HNO3 (etc.) which PSAT does

– Must apportion O and N in NO2

independently

Odd-oxygen in NO2 (ONO)

Follow the O:NO + OOO ONO

ONO + hv NO + O

O + OO OOO

NOX recycling

Follow the N:

OH + NO2 HNO3

HNO3 + hv OH + NO2

also for PAN and nitrates

Purpose of OSAT Update

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OSAT (1995-2004)• OSAT uses 4 Reactive Tracers for each Source Group:

– Ni -- Nitric oxide (NO) and nitrogen dioxide (NO2) emitted by source group i

– Vi -- VOC emitted by source group i– O3Ni -- O3 formed under NOX-limited conditions from Ni

– O3Vi -- O3 formed under VOC-limited conditions from Vi

• NOX- vs. VOC-limited determined by ratio of instantaneous production of hydrogen peroxide and nitric acid– [PH2O2]/[PHNO3] < 0.35 NOX-limited (Sillman, 1995)

• When total change in ozone (ΔO3) is positive, allocate ΔO3 to Source Groups based on contribution of limiting precursor (N or V)

• When ΔO3 is negative, detriment Source Groups O3N and O3V equally on total percentage basis

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OSAT2 (2005-2015)• OSAT2 recognizes that ozone formation and destruction

can occur at the same time• Calculate ozone destruction (DΔO3) due to reactions:– O3 + VOC reactions since these remove ozone;– O(3P) + VOC reactions since these effectively remove ozone;– O(1D) + H2O reaction since this effectively removes ozone;

– HOX + O3 reactions that do not re-form ozone.

• Ozone formed PΔO3 = [ΔO3 – DΔO3]

• Allocate PΔO3 and DΔO3 to Source Group reactive tracers using same reactive tracers and rules as OSAT

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OSAT3 (2015+)• Track odd oxygen and nitrogen recycling• Need many more (10) reactive tracers than OSAT/OSAT2 (4):

– Vi VOC emitted by source group i– NITi Nitric oxide (NO) and nitrous acid (HONO)– RGNi Nitrogen dioxide, nitrate radical (NO3) and dinitrogen pentoxide (N2O5)– TPNi Peroxyl acetyl nitrate (PAN), analogues of PAN and peroxy nitric acid (PNA)– NTRi Organic nitrates (RNO3)

– HN3i Gaseous nitric acid (HNO3)– O3Ni O3 formed under NOX-limited conditions from Ni

– O3Vi O3 formed under VOC-limited conditions from Vi

– OONi Odd-oxygen in NO2 formed from O3Ni

– OOVi Odd-oxygen in NO2 formed from O3Vi

• Also update PSAT with more tracers to be consistent with OSAT3

OSAT2 vs. OSAT 3 Comparison

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OSAT2 vs. OSAT 3 Comparison ofLocal Contributions

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Updates to Ozone Source Apportionment

• OSAT3 completed and operational– Apportions odd-oxygen in

NO2

– Tracks NOX-recycling

• OSAT3 uses more tracers– Larger output, slower runs

• Contributions change– Generally smaller local

contribution– Generally larger transported

contribution

• NO2 explicitly tracked as own tracer species– Can now do explicit

contributions for 1-hour NO2 assessments instead of using RGN species

• PSAT also updated– N tracking compatible with

OSAT3• Publicly released with next

version of CAMx (V6.3?) in 2016

2011 Detailed 4 km Apportionment• SA Plan presents several

possibilities:– Summer ozone SA with

more geographic subregions and source subcategories

– Winter ozone period– PM2.5 or visibility events

• New ideas:– OSAT3/PSAT3– Other???

• Limited by available resources