The Revised Aerosol Scheme of ECHAM5HAMMOZ

1
The Revised Aerosol Scheme of ECHAM5-HAMMOZ
COSMOS General Assembly 15/06/2009 Berlin Philip
Stier1, Rosalind West1, Jan Kazil2, Declan
ODonnel2, Kai Zhang2, Johann Feichter2,
Johannes Quaas2, Ulrike Lohmann3, Sylvaine
Ferrachat3, Corinna Hoose4, Betty Croft5 1
Atmospheric, Oceanic and Planetary Physics,
University of Oxford 2 Max Planck Institute of
Meteorology, Hamburg 3 Swiss Federal Institute
of Technology, Zurich 4 University of Oslo 5
University of Halifax
DEPARTMENT OF PHYSICS
2
Aerosols ClimateDirect Aerosol Effects
Introduction
SeaWIFS true-color satellite image
(25/08/2000) (From http//visibleearth.nasa.gov)
3
Aerosols, Clouds ClimateIndirect Aerosol
Effects
Introduction
Motivation
MODIS true-color satellite image
(04/03/2009) (From http//visibleearth.nasa.gov)
4
Indirect Aerosol Effects
Aerosols, Clouds ClimateIndirect Aerosol
Effects
Cloud Albedo Effect Twomey (1977)
Introduction
Motivation
MODIS true-color satellite image
(04/03/2009) (From http//visibleearth.nasa.gov)
5
Indirect Aerosol Effects
Aerosols, Clouds ClimateIndirect Aerosol
Effects
Cloud Lifetime Effect Albrecht (1989)
Introduction
Motivation
MODIS true-color satellite image
(04/03/2009) (From http//visibleearth.nasa.gov)
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HAM - Aerosol Representation
Considered Compounds Sulfate Black Organic
Sea Salt Mineral Dust Carbon Matter
The ECHAM5-HAM Model
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HAM - Aerosol Representation
Considered Compounds Sulfate Black Organic
Sea Salt Mineral Dust Carbon Matter Resolve
aerosol size-distribution by 7 log-normal modes
The ECHAM5-HAM Model
8
HAM - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005)
• Condensation of sulfate on existing particles
• Coagulation
• Nucleation of sulfate particles
• Inter-modal transfer
• Thermodynamical equilibrium with water vapour

The ECHAM5-HAM Model

• Simulation setup throughout this talk
• Paired simulations nudged to year-2000 ECMWF
  ERA-40 meteorology

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HAMV2 - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005, in preparation)
• Condensation of sulfate on existing
  particles Prognostics SOA scheme with explicit
  gas/liquid partitioning (Declan ODonnell)
• Coagulation
• Binary nucleation of sulfate particles
• Inter-modal transfer
• Thermodynamical equilibrium with water vapour

The ECHAM5-HAM Model
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HAMV2 - Secondary Organic Aerosols
2-product SOA scheme with explicit gas/liquid
partitioning (Declan ODonnell)
The ECHAM5-HAM Model

• Simulation setup throughout this talk
• Paired simulations nudged to year-2000 ECMWF
  ERA-40 meteorology

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HAMV2 - Secondary Organic Aerosols
2-product SOA scheme with explicit gas/liquid
partitioning (Declan ODonnell)
Annual mean biogenic SOA burden 0.46 Tg
Annual mean anthropogenic SOA burden 0.08 Tg
The ECHAM5-HAM Model
12
HAMV2 - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005, in preparation)
• Condensation of sulfate on existing
  particles Prognostics SOA scheme with explicit
  gas/liquid partitioning (Declan ODonnell)
• Coagulation
• Binary nucleation of sulfate particles Neutral
  and charged nucleation, activation and kinetic
  SOA/SO4 boundary layer nucleation, cosmic ray
  ionisation, updated time integration (Jan Kazil)

The ECHAM5-HAM Model
13
HAMV2 - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005, in preparation)
• Condensation of sulfate on existing
  particles Prognostics SOA scheme with explicit
  gas/liquid partitioning (Declan ODonnell)
• Coagulation
• Binary nucleation of sulfate particles Neutral
  and charged nucleation, activation and kinetic
  SOA/SO4 boundary layer nucleation, cosmic ray
  ionisation (Jan Kazil)
• Inter-modal transfer
• Thermodynamical equilibrium with water
  vapour Updated thermodynamics for water uptake
  to ?- Köhler (Declan ODonnell)

The ECHAM5-HAM Model
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HAMV2 Revised Water Uptake
Updated thermodynamics from ZSR to ?- Köhler
(Declan ODonnell)
Hydrophilic coarse mode radius µm
ZRS based (Old)
?- Köhler (New)
The ECHAM5-HAM Model
15
HAMV2 - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005, in preparation)
• Condensation of sulfate on existing
  particles Prognostics SOA scheme with explicit
  gas/liquid partitioning (Declan ODonnell)
• Coagulation
• Binary nucleation of sulfate particles Neutral
  and charged nucleation, activation and kinetic
  SOA/SO4 boundary layer nucleation, cosmic ray
  ionisation (Jan Kazil)
• Inter-modal transfer
• Thermodynamical equilibrium with water
  vapour Updated thermodynamics for water uptake
  to ?- Köhler (Declan ODonnell)
• Generalised modal structure (Declan ODonnell)
• Explicit below-cloud and in-cloud scavenging
  schemes (Betty Croft)
• Introduced LW and revised SW aerosol radiation
  scheme (Stier et al., 2007)

The ECHAM5-HAM Model
16
HAMV2 - Aerosol Representation

• Considered Compounds
• Sulfate Black Organic Sea Salt Mineral
  Dust Carbon Matter
• Resolve aerosol size-distribution by 7 log-normal
  modes
• Mode size, mixing state, and composition
  predicted by microphysical aerosol module M7
  (Vignati et al., 2005, in preparation)
• Aerosol-cloud coupling (Lohmann et al., 2007)
• prognostic treatment of CDNC and ICNC (Lohmann
  et al., 2002)
• alternative approaches for aerosol activation
  into cloud droplets
• - semi-empirical CCN f(CN ,w) related to
  prognostic aerosol number and updraft
  velocity (Lin Leaitch, 1997)
• - explicit Köhler theory based activation
  (Abdul-Razzak and Ghan, 2000)

The ECHAM5-HAM Model
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HAMV2 - Aerosol Activation
Annual mean activated stratiform cloud droplets
per source mode
Results
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Aerosol Radiative Effect (Direct Indirect)
Annual-mean anthropogenic SWLW TOA radiative
effects
Results
Empirical (Lin Leaitch, 1997)
Explicit (Abdul-Razzak and Ghan, 2000)
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Preliminary Evaluation
Process oriented statistical evaluation strategy
applied in the AeroCom Indirect Intercomparison
Study (Quaas et al., in preparation)
Observed relationships between cloud and aerosol
properties
CDNC
Aerosol Number (Ramanathan et al., 2001)
Results
Saturation of effects (and theory) suggest
logarithmic dependency
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Preliminary Evaluation
Process oriented statistical evaluationGlobal
annual mean slopes for Cloud Droplet Number
Concentration
Satellite
Model
Results
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Preliminary Evaluation
Process oriented statistical evaluationGlobal
annual mean slopes for Liquid Water Path
Satellite
Model
Results
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Summary Conclusions

• ECHAM5-HAMMOZ has been substantially revised
• New formulations ensure consistency
• The simulated direct and indirect radiative
  effects are surprisingly resistant to
  significant model changes, such as aerosol
  activation - microphysical compensation -
  importance of the base model
• Detailed representations in ECHAM-HAMMOZ allow
  process studies and hypothesis testing
• Ideal level of complexity not obvious and will
  depend on application

DEPARTMENT OF PHYSICS
Systematic studies on aerosol model uncertainty
and complexity under observational constraints
will be performed in AEROS project using
ECHAM5-HAMMOZ and the UK equivalent UKCA
Advertisement We are looking for an AEROS
post-doctoral researcher in the Department of
Physics at the University of Oxford speak to
me
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HAMV2 - Aerosol Representation
Considered Compounds Sulfate Black Organic
Sea Salt Mineral Dust Carbon Matter Resolve
aerosol size-distribution by 7 log-normal
modes Mode size, mixing state, and composition
predicted by microphysical aerosol module M7
(Vignati et al., 2005, in preparation)
Mixing state configuration
The ECHAM5-HAM Model
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ECHAM5-HAM Clouds

• Extension of standard ECHAM5 cloud scheme
• Prognostic treatment of CDNC and ICNC (Lohmann
  et al., 2002, )

• Alternative schemes for aerosol activation
• Empirical approach (Lin Leaitch, 1997)

ECHAM5-HAM Aerosol-cloud coupling

• Explicit activation (Abdul-Razzak and Ghan,
  2000 Fountoukis Nenes, 2005)

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Anthropogenic Perturbations to the Climate System
Current best estimate of anthropogenic radiative
forcing
Introduction
Intergovernmental Panel on Climate Change
estimate of present day global annual mean
anthropogenic radiative forcings (Solomon et al.,
2007)
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AeroCom Aerosol Intercomparison Study
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Anthropogenic Perturbations to the Climate System
Current best estimate of anthropogenic radiative
forcing
Introduction
Intergovernmental Panel on Climate Change
estimate of present day global annual mean
anthropogenic radiative forcings (Solomon et al.,
2007)
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Anthropogenic Perturbations to the Climate System
Including uncertain indirect aerosol effects
Total Aerosol
Cloud lifetime effect
Lohmann Feichter (2005)
-1.2 -1.9 to -0.5
Introduction
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Anthropogenic Perturbations to the Climate System
Including uncertain indirect aerosol effects
Total Aerosol
Cloud lifetime effect
Lohmann Feichter (2005)
-1.2 -1.9 to -0.5
Introduction
0.4 -0.3 to 2.4