Modelling Capabilities for Aerosols and Climate at CCCma

Knut von Salzen

Canadian Centre for Climate Modelling and Analysis (CCCma) Environment Canada, Victoria, British Columbia, Canada

Acknowledgements: M. Namazi, J. Li, J. Cole, J. Scinocca, J. Fyfe, N. Gillett (CCCma)W. R. Leaitch, S. Sharma, L. Huang (CCMR, Environment Canada)A. Herber (AWI Bremerhaven)

knut.vonsalzen@ec.gc.ca www.cccma.ec.gc.ca

General features

• Resolution: T63 (ca. 2.8°), 49 levels to approx. 1hPa

• Spectral advection, hybridization of tracer variable, physics filter

• Orographic and non-orographic gravity wave drag

• Radiation: Correlated-k distribution and Monte carlo Independent Column Approximation (McICA) methods

• Local and non-local turbulent mixing

• Mass flux schemes for deep and shallow convection

• Prognostic cloud liquid water and ice, statistical cloud scheme

New features

• Most recent version of the CLASS land surface scheme (version 3.6)

• Parameterizations for snow microphysics and snow albedo

• Prognostic aerosol microphysics (size distributions) for sulphate, sea salt, mineral dust, hydrophobic and hydrophilic black and organic carbon

• Improved direct radiative aerosol forcings (internally mixed aerosol)

• 1st and 2nd aerosol indirect effects, using online non-adiabatic parcel model

• Absorption of solar radiation by black carbon in cloud droplets

Canadian Atmospheric Global Climate Model (CanAM4.2)

Large Increases in Black Carbon Emissionsfrom Human Activities

Historic(Lamarque et al., 2010)

Future(Moss et al., 2010)

Anthropo-genic

VegetationFires

FSUN AmericaEurope

S+E Asia

Other

FSUN AmericaEuropeS+E Asia

Other

RCP6.0

RCP8.5

RCP6.0

RCP2.6

RCP8.5

RCP2.6

Land

BC

Ocean

BCBC

Black Carbon Sources + Sinks in CanESM4.2-PAM

BC

hydrophobic

hydrophilic

24 hrs

gravitationalsettling

wet depositionSinks

dry deposition

coagulation& condensation

condensationnucleation

& coagulation

inorganic & organicvapours

mechanical production(sea salt, mineral dust)

approx. dry particle radius (µm)

emissions

Sources

Aerosol Microphysical Processes in CanAM4.2

Droplet Activation and Growth

25 cm/s50 cm/s100 cm/s 200 cm/s

updraft wind speedCircles: New numerical solutionBullets: Detailed parcel model (Shantz and Leaitch)

Water-solubleorganics in aerosol

Water-insoluble organics in aerosol

heig

ht

(m)

supersaturation (%) supersaturation (%)

CDNC (m-3)

CDNC (m-3)

cloud layer

adiabaticair parcel

heig

ht

(m)

• Analysis of radiative forcings of different types of aerosol in CanAM4.2 by emission region and sector

• Validation of temporal variability in simulated aerosol concentrations on multi-year and seasonal time scales using surface observations

• Validation of vertical profiles and horizontal BC concentration distributions based on aircraft observations

• Analyze roles of biomass and fossil fuel emissions for black carbon concentrations through comparisons with isotopic data

• Investigate contributions of Arctic DMS emissions to aerosol burdens

• Detection and attribution of changes in Arctic climate to changes in aerosol emissions

• Climate mitigation scenario simulations for black carbon

Summary of Plans for Aerosol and Climate Modelling

- Lookup table function of: SWE, underlying surface albedo, solar zenith angle, snow grain size, BC concentration, wavelength interval

- Diffuse albedo, direct albedo, diffuse transmission, and direct transmission

- Single layer of snow over bare ground (consistent with CLASS)

- Detailed offline DISORT calculations at 280 wavelengths. Results averaged over CCCma solar radiation bands

- Total albedo for each band is weighted average (based on incident radiation) of direct and diffuse albedo

SWE (kg/m2) SWE (kg/m2)

Gra

in s

ize

(mic

rons

)

Diffuse albedo Diffuse trans

Parameterization of Snow Albedo

Means for0.2-0.69 microns, black surface, θ=0o

droplets/cm3

Cloud Droplet NumberConcentration in low Clouds

for JJA

Obs: MODIS, 2001(Bennartz, pers. comm.)

Improved Simulation of Cloud Droplets and Aerosol Forcings

Satellite observations

CanAM with aerosol microphysics CanAM with bulk aerosol scheme

dry + melt-freeze

metamorphism

Atmosphere

Surface Snow Layer

snowfallBC dry + wet

deposition

BC melt waterscavenging

Parameterizations for Snow Microphysics

Clear-Sky Planetary Albedo BiasesMarch-April-May (MAM) June-July-August (JJA)

New snow albedoparameterization

CLASS 3.6

(Anomalies vs. CERESEBAF V2.7, 2003-2008,

masked by modelled SWE)

Improved biases from new parameterizations for snow albedo

Simulation of Multicomponent Aerosols withthe PLA Aerosol Model (PAM)

Example from application of PAM in a developmental version of the Canadian atmospheric global climate model (CanAM4-PAM)

Effects of Aerosols on Clouds & Climate

more reflection:Cloud albedo effect

less precipitation:Cloud lifetime effect

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The strength of aerosol radiative forcings from aerosol/cloud interactions depends on how strongly cloud droplet concentrations respond to changes in aerosol concentrations

Extended Canadian Earth System Model (CanESM4.2-PAM)

• Under development. Frozen model expected to become available Oct 2013.

• Developmental atmospheric component: CanAM4-PAM.

• Fully coupled 3D model for atmosphere, land surface, ocean, cryosphere, and carbon cycle.

• Resolution in atmosphere: T63 (ca. 2.8°), 49 levels to approx. 1hPa.

• Spectral/hybrid representation of large-scale advection of tracers.

• Prognostic aerosol size distributions for Sulphate, sea salt, mineral dust, hydrophobic and hydrophilic black and organic carbon using interactively coupled Piecewise Lognormal Approximation (PLA) Aerosol Model (PAM). Standard aerosol processes: Emissions, transport, dry and wet deposition, coagulation, binary homogeneous nucleation, chemical production for clear- and cloudy-sky.

• Interactive direct radiative calculations for internally mixed hydrophilic BC/OC/SO4.

• 1st and 2nd indirect effects using online non-adiabatic parcel model.

• Absorption of solar radiation by BC in cloud droplets.

• New parameterization for absorption of solar radiation by BC in snow based on tabulated, pre-calculated albedo and prognostic parameterization for BC snow concentration and grain size (single layer).