Download Gail Tonnesen for VISTAS (CMAQ-AIM and CAMx)

Preliminary Results
CMAQ and CMAQ-AIM with SAPRC99
Gail Tonnesen, Chao-Jung Chien, Bo Wang, UC Riverside
Max Zhang, Tony Wexler, UC Davis
Ralph Morris, Steven Lau, Bongyoung Koo
ENVIRON International Corporation T.W. Tesche, Dennis McNally
and Greg Stella
Alpine Geophysics
RPO Meeting, Denver, CO, May 25, 2004
Sectional PM Models
CMAQ-AIM
Gas-Phase
SAPRC99
CAMx4
CMAQ-MADRID1
CMAQ-MADRID2
CACM
CB4, SAPRC99
CB4, RADM2
RADM2_CI4
RADM2 with four-product
isoprene chemistry
Caltech Atmospheric
Chemistry Mechanism
Inorganic
AIM
ISORROPIA
ISORROPIA
ISORROPIA
Organic
Dynamic Partit.
(UC Davis)
SOAP
Odum/Griffin
Algorithm
AER/EPRI/Caltech
(AEC) Algorithm
Aqueous
RADM
RADM
CMU, RADM
CMU, RADM
Size
Nine-Section
Two-Section
(Fine/Coarse)
Two-Section
(Fine/Coarse)
Multiple-Section (>2)
CMAQ-AIM
• Aerosol Inorganic Module (AIM) Clegg et al.
• CMAQ-AIM uses simplified AIM
thermodynamics to reduce computation cost.
• Sectional aerosol algorithm (9 sections).
• Uses SAPRC99 gas chemistry.
SOA in CMAQ-AIM
• Simplified SOA speciation: uses 1
anthropogenic and 1 biogenic SOA.
• Dynamic gas-particle partitioning:

j

j 0
2

D
D
C

y
dmi
g
p
i
i Ci

8
dt
1
D pj
j

NaCl Thermodynamics
• Forms coarse mass NaNO3
– Should give reduced fine NO3 in CMAQ-AIM
• CMAQ includes Sea salt species but chemistry
is not yet implemented in ISORROPIA.
• CMAQ-AIM includes sea salt.
Sea Salt Emissions
• Used EPA code for sea salt emissions:
– Only represented open ocean emissions.
• Added new code to represent surf zone
emissions.
• Simple approximations of surf zone area:
– 100 m width
– If cell is between 20 and 80% water use cell full
length as coast.
CMAQ-AIM Evaluation
• CMAQ-AIM is still under development.
• Initial Comparison of CMAQ-AIM to
CMAQ was presented to VISTAS February
2004.
• More recent results still being analyzed
SO4 (IMPROVE); CMAQ-AIM vs. CMAQ
US (FB, -14% vs. -2%)
Vistas States (FB, -30% vs.-15%)
CMAQ-AIM Summary
• CMAQ-AIM tends to have lower predictions
larger negative bias compared to CMAQ
• Should we look at the size bins that are being
included in PM2.5?
• Does CMAQ-AIM have some SO4 and NO3
mass in larger size bins?
• Still need to look at sea salt for recent
simulation.
Comparison and Diagnostic
Evaluation of Air Quality Models for
Particulate Matter:
CAMx, CMAQ, CMAQ-MADRID
Zion Wang, Chao-Jung Chien and Gail Tonnesen
University of California, Riverside
Eladio M. Knipping and Naresh Kumar
EPRI
Modeling Episode
• Southern Oxidant Study (SOS)
– June 29 to July 10, 1999
• Meteorology processed from MM5 Simulations
– MCIP2.2: CMAQ, CMAQ-MADRID
– mm5camx: CAMx
• Emissions files courtesy of TVA
• Simulation
– 32-km horizontal resolution without nesting
• Sensitivity Simulation
– Increase ammonia emissions by 50% across-the-board
Summary of EPRI Study
No single model is the “performance winner”.
• All models over-estimated aerosol sulfate concentrations. CAMx
showed a higher tendency to over-estimate aerosol sulfate
concentration across a wide region of the domain compared to
CMAQ and CMAQ-MADRID.
• CMAQ under-estimated aerosol nitrate concentrations by a factor of
~2.5, whereas CMAQ-MADRID and CAMx over-estimated nitrate by
a factor of ~3. However, CAMx exhibited a higher propensity to
over-estimate nitrate in the southeast than CMAQ-MADRID.
• All models under-estimated organic mass. However, CMAQ
predicted the least organic mass of all three model
• The models responded differently to changes in
ammonia emissions.