proposed aerosol treatment for cam4 steve ghan, richard easter, xiaohong liu, rahul zaveri pacific...
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Proposed Aerosol Treatment for CAM4
Steve Ghan, Richard Easter, Xiaohong Liu, Rahul ZaveriPacific Northwest National Laboratory
precursor emissions
coagulation
resuspension
new particle formation
subcloudscavenging
wateruptake
primary emissions
aqueouschemistry
drydeposition
activation
diffusion
condensationevaporation
oxidation
scavenging
Goal: Develop a complete and computationally efficient representation of the aerosol for exploring the competing and complementing mechanisms by which natural and anthropogenic aerosols influence clouds and the cycles of water and energy.
precursor emissions
coagulation
resuspension
new particle formation
subcloudscavenging
wateruptake
primary emissions
aqueouschemistry
drydeposition
activation
diffusion
condensationevaporation
oxidation
scavenging
Current Weaknesses in CAM
• Aerosol species are externally mixed (individual particles are composed of only a single species).
Current Weaknesses in CAM
• Aerosol species are externally mixed (individual particles are composed of only a single species).
• Their size distribution is prescribed (number is diagnosed from the predicted mass).– Processes that should only affect mass also
affect number.– Processes that only affect number are
neglected.
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Primary CarbonnumberBChydrophobic OC
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Primary CarbonnumberBChydrophobic OC
coagulationcondensation
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Accumulationnumbersulfateammoniumnitratesecondary OChydrophobic OCBC
Primary CarbonnumberBChydrophobic OC
coagulationcondensation
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Accumulationnumbersulfateammoniumnitrate secondary OChydrophobic OCBC
Primary CarbonnumberBChydrophobic OC
Fine Soil Dustnumbersoil dustsulfatenitrate secondary OC
Fine Sea Saltnumbersea saltsulfatenitrate secondary OC
Coarse Soil Dustnumbersoil dustsulfatenitrate secondary OC
Coarse Sea Saltnumbersea saltsulfatenitrate secondary OC
coagulationcondensation
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Accumulationnumbersulfateammoniumnitrate secondary OChydrophobic OCBC
Primary CarbonnumberBChydrophobic OC
Fine Soil Dustnumbersoil dustsulfatenitrate secondary OC
Fine Sea Saltnumbersea saltsulfatenitrate secondary OC
Coarse Soil Dustnumbersoil dustsulfatenitrate secondary OC
Coarse Sea Saltnumbersea saltsulfatenitrate secondary OC
coagulationcondensation
All modes log-normal with prescribed width.
Total tracers: 25 (33)
Proposed Aerosol Treatment for CAM4Steve Ghan, Richard Easter, Xiaohong Liu, Rahul Zaveri
Pacific Northwest National Laboratory
Aitkennumbersulfateammonium
Accumulationnumbersulfateammoniumnitrate secondary OChydrophobic OCBC
Primary CarbonnumberBChydrophobic OC
Fine Soil Dustnumbersoil dustsulfatenitrate secondary OC
Fine Sea Saltnumbersea saltsulfatenitrate secondary OC
Coarse Soil Dustnumbersoil dustsulfatenitrate secondary OC
Coarse Sea Saltnumbersea saltsulfatenitrate secondary OC
coagulationcondensation
All modes log-normal with prescribed width.
Total tracers: 25 (33)
Cloud-borne aerosol predicted but not advected.
Aerosol Processes
precursor emissions
coagulation
resuspension
new particle formation
subcloudscavenging
wateruptake
primary emissions
aqueouschemistry
drydeposition
activation
diffusion
condensationevaporation
oxidation
scavenging
Process Treatment
• New particle formation: binary homogeneous• VOC oxidation and condensation separated• Condensation: mass transfer theory• Coagulation: Brownian within, between modes• Renaming from Aitken to accumulation• Scavenging: activation of number and mass for each mode,
number depletion by droplet collision/coalescence• Water uptake: Kohler theory for internal mixture, with
hysteresis dependent on previous aerosol water• Optical properties: parameterization in terms of wet
refractive index and wet surface mode radius
Schedule
• March 2006: Select version of CAM to start with• March 2007: Complete application and first
simulation• September 2007: Complete evaluation and
refinement• December 2007: Complete merge with
developmental trunk