Evaluation of CMAQ SOA during CALNEX g with Consideration of - - PowerPoint PPT Presentation

Evaluation of CMAQ SOA during CALNEX g with Consideration of Volatility Space

Annmarie G Carlton K R Baker Annmarie G. Carlton, K. R. Baker, T.E. Kleindienst, J.H. Offenberg, M. Jaoui

California Nexus

R f t f C lT h (P d ) B k fi ld (S J i V ll ) Roof top of CalTech (Pasadena) Bakersfield (San Joaquin Valley)

For additional model details see Kelly et al. Poster

CMAQ exhibits a persistent negative bias in OA mass prediction.

Motivation

Q p g p Community consensus that it is a consequence of 2o processes.

Missing VOCs? More SV products?

Possibly, but even when precursors are perfectly known (e.g., Parikh et al., (2010)) models still fail.

Missing Processes? Missing Processes?

Application of theory needs expanding: “Like” into “Like” means polar organic compounds into polar solvents (water) (Parikh et al., 2010; Wayne et al., 2010; Pankow and Barsanti,

2009) 009)

Total carbon comparisons are insufficient to guide effective mechanism d l t E l ti f th d h i l t i iti l

• development. Evaluation of theory and chemical tracers is critical.

accumulation mode

• rganic PM

cloud water hi h i ld long alkanes

AALK

SV_ALK ∙OH SV_TOL1 SV TOL2

• CMAQ employs Odum type

AOLGA AORGC

·OH

ution

high-yield aromatics low-yield

AALK ATOL1, ATOL2

SV_TOL2

SV_XYL1 SV XYL2

·OH/NO

Q p y yp parameterizations for SOA

dissolu

aromatics

AXYL3 ATOL3 ABNZ3

AXYL1, AXYL2

ABNZ1, ABNZ2

SV_XYL2

SV_BNZ1 SV BNZ2

• The saturation vapor pressures of

partitioning species in CMAQ span 5

AOLGB AISO3

glyoxal methylglyoxal

benzene

POA

SV_TRP1 SV TRP2 ASQT ATRP1, ATRP2

·OH/HO2

SV_BNZ2

p g p Q p

• rders of magnitude

H+

VOCs monoterpene

SV_TRP2

SV_SQT

·OH,O3, or NO3

AISO1, AISO2

• CMAQ partitioning species retain

chemical idenity and can be traced to

IONS IONS

isoprene sesquiterpenes

SSIONS SSIONS IONS

SV_ISO1, SV_ISO2

,

3, 3

y VOC precursor – important consideration for source attribution

EMISSI EMISSI

isoprene

EMIS EMIS EMISSI

Pathways do not contribute to SOA Carlton et al., ES&T 2010

Model Formulations to Model SOA Model Formulations to Model SOA

aromatics alkanes monoterpenes sesquiterpenes isoprene http://www.epa.gov/AMD/ModelDevelopment/aerosolModule.html

Absorptive‐Partitioning Theory

( )

⎥ ⎦ ⎤ ⎢ ⎣ ⎡ + ° = =

− 6 , ,

10 760 1600 1

• m

RT Q Q TSP s i aer i P

MW RT f e T a N p TPM C C K

v

ζ ⎦ ⎣ ° ,

,

10 1600

i

• m

i L i gas

MW p TPM C ζ

surface adsorption

• rganic-phase

absorption p absorption

6 , ,

10 760

i aer i

• m

MW p RT M C C K ζ ° = =

Expressed partitioning behavior of each compound as a function of temperature and organic phase composition

, ,

10

i

• m

i L

• i

gas

MW p M C ζ

function of temperature and organic-phase composition Mo is the organic-phase mass concentration Notation differs slightly from primary reference

– Ref: Pankow, Atmos. Env. (1994) – Slide courtesy of P. Bhave

Notation differs slightly from primary reference

Theory: applied to toluene SOA modeling

Odum type 2 product Odum type 2 product

Ng et al. (2007)

Volatility basis set

Hildebrandt et al., (2009) P ikh t l AE 2011 Parikh et al., AE, 2011

CMAQ and GEOS‐Chem have multiphase (heterogeneous) SOA processes

Modeling Overview

• May‐July 1, 2010 episode
• CMAQ v4.7.1 (N2a)
• CB05 & AERO5
• WRF v3 2 (MCIP v3 6)
• WRF v3.2 (MCIP v3.6)
• BEIS v3.14
• WRF 2 m temperature and WRF

shortwave downward radiation

• Horizontal grid cell size = 4 km
• 2005v2 NEI anthropogenic

emissions for U.S.

• Mexico emissions based on 1999
• NX = 236, NY = 317
• Lambert projection centered at (‐97,40)

with true latitudes 33 and 45

• Domain origin (‐2416 km, ‐832 km)
• Mexico emissions based on 1999

inventory (Mexico a minimal influence during CalNex). For additional model details see Kelly et al. Poster

Conclusions

Missing gaps in CMAQ’s SOA volatility distribution when CB05 is g g p y employed. Organic mass “aging” (VOC SV_VOC SV_OA LV_OA) assumptions need some re‐visiting # of carbons in SV species ≠ to parent VOC ‐ # of carbons in SV species ≠ to parent VOC ‐ assigned OM:OC ratios should be calculated for individual, representative chemicals , p Chemical SOA tracers are underpredicted for all measurable i 2 CA l i b d l species at 2 CA locations: urban and rural

– Some chemical identity is lost during oligomerization – Tracers are not conservative or OM:OC is not constant from chamber to field – Gas phase VOC/SV_VOC precursors mixing ratios are not correct,

Acknowledgements

• James Kelly
• James Kelly
• Rich Mason
• Laura Reynolds, Allan Beidler, James Beidler, Chris Allen