an investigation of ammonia and inorganic particulate matter in california during the calnex...
TRANSCRIPT
An Investigation of Ammonia and Inorganic Particulate Matter in California
during the CalNex Campaign
AGU Fall Meeting5 December 2012
Luke D. Schiferl, Colette L. Heald, John B. Nowak, John S. Holloway,
J. Andy Neuman, Roya Bahreini, Ann M. Middlebrook, Christine Wiedinmyer, and Stuart A. McKeen
Funding:
NH3SOX NOX
Emissions
Gas-Particle Partitioning
NH3
H2SO4
HNO3
NH4+
SO42-
NO3-
Deposition
Dry Wet
Transport
NH3
California: High Nitrogen Environment
PM2.5 Human Population Increase from 2010
by 2020 2040
20 %10 %
60 %15 %
[State of California, 2012]
01 – 6,2976,298 – 12,41912,420 – 23,95523,956 – 39,79239,793 – 87,028
[California Energy Commission, 2008]
[EPA, 2011]
LA
SFUrban + Rural N Sources
CalNex Field StudyMay-June 2010
NOAA WP-3D aircraft18 flights
Species Measurement Technique Resolution
NH3chemical ionization mass
spectrometry
1 sSO2 pulsed UV fluorescence
HNO3chemical ionization mass
spectrometry
NH4+
aerosol mass spectrometry 10 sSO4
2-
NO3-
Used in this analysis
GEOS-Chem chemical transport model used to interpret observations
• Driven by assimilated meteorology• 0.5° x 0.667° horizontal resolution
over North America
• NEI-2005 anthropogenic emissions
SOX
Altitude[km]
NH3 NOX
[Mg N/mo]
May
[Mg S/mo] [Mg N/mo]
Comparing CalNex Observations with GEOS-Chem Simulation
City Valley
ValleyN ≈ 800
CityN ≈ 1600
CalNex ObsModel
CalNex ObsModel
Median Concentrations Shown
NH3SOx NOx
Emissions
Gas-Particle Partitioning
NH3
H2SO4
HNO3
NH4+
SO42-
NO3-
Deposition
Dry Wet
Transport
NH3
Simulating Gas-Particle Partitioning
ISORROPIA IINHx
SO42-
TNO3
Na+
Cl-
TRH
NH3
NH4+
HNO3
NO3-
GEOS-Chem
H2SO4 + NH3
HNO3 + NH3
2 NH4+
SO42-
NH4 +
NO3-
If remaining NH3…First…
f(T, RH, ions)
GEOS-Chem T and RH v. CalNex ObservationsValleyCity
Fountoukis and Nenes [2007]
CalNex ObsModel
CalNex ObsModel
+/- 1 °C
Simulation is Insensitive to Temperature Uncertainty
ValleyCityCalNex Obs
ModelISORROPIA
+/- 1 °C
CalNex ObsModel
ISORROPIA +/- 1 °C
Uncertainty in RH Produces Small Differences in Ammonium Nitrate
City Valley
+/- 10 % RH
CalNex ObsModel
ISORROPIA +/- 10 % RH
CalNex ObsModel
ISORROPIA +/- 10 % RH
Simulated N Deposition in GEOS-Chem
Nitrogen Deposition Dominated by Dry Removal Processes during CalNex
Wet Deposition Dry Deposition
May
June
California
Wet Dry
NH3
NH4+
HNO3
NO3-
Total Deposition11.7 [Gg N/mo]
Virtually no summertime wet deposition confirmed by NADP measurements
NHX
May/June Mean
[Mg N/mo]
GEOS-Chem v. CASTNET Simulated Dry Deposition Velocity Evaluating Dry Deposition
CASTNET: May-June 2007-2009
0.5x SO2 Dry Deposition Velocity v. CalNex Observations
City
ValleyCity
CalNex ObsModel
Modified Model Dep
CASTNET Sites
*NH3 deposition not measured by CASTNET
Scaling Up EmissionsAll NEI-2005
Sources Livestock
5x Livestock - EverywhereEast LA Livestock to 12 Gg yr-1
3x - North Valley10x - South Valley
NH3
SO2
Modified Anthropogenic Emissions
Nowak et al. [2012]
[Mg N/mo]May
[Mg S/mo]May
Increasing Emissions Reduces Model Bias in California
City Valley
CalNex ObsModel
Modified Model Emissions
CalNex ObsModel
Modified Model Emissions
Improved Simulation of Near-Surface Concentrations
Standard ModifiedCalNex Obs
Median, lowest 1 km
Standard ModifiedCalNex Obs
ValleyCity
Model Model
Implications in California
Surface Concentration Column Concentration
June
Dec
embe
r
Jun Dec
Mean, lowest 1 km
City Valley
Jun Dec
Export of Excess Ammonia
Ammonia and Seasonality of PM
NH3
Conclusions
Further exploration with NH3 satellite retrievals where observations limited
Investigate impacts of simulating NH3 bi-directional flux
Emissions of ammonia and sulfur dioxide are underestimatedin California for May/June.
Simulated June PM concentrations higher in LA than in the Valley; NH3 critical for this formation
Reverse situation in December: LA becomes NH3 limited and Valley PM increases
Excess NH3 from Valley is exported downwind in spring/summer and potential exists for additional PM formation should acid levels increase
Future WorkSummertime 2009
IASI Column Concentration