implementation of sulfate and sea-salt aerosol microphysics in geos-chem win trivitayanurak &...

Implementation of Sulfate and Sea-Salt

Aerosol Microphysics in GEOS-Chem

Win Trivitayanurak & Peter AdamsCarnegie Mellon University

3rd GEOS-Chem Users’ MeetingApril 11, 2007

11/4/07

Implementation Aerosol Microphysics in GEOS-Chem Win T. 2

Radiative Forcing EstimatesGlobal-average estimates for 2005, relative to 1750

Level of scientific understanding

+2.6 W/m2

-1.2 W/m2

IPCC (2007)

+1.6 W/m2

Must improve aerosol indirect effect estimate!

11/4/07


Improving Aerosol Microphysics

GISS GCM-II’• Produce its own

meteorology• Cannot predict at a

specific time

GEOSCHEM• Driven by assimilated

meteorology• Good for predicting at

specific times for comparison with observations

MicrophysicsMicrophysics

Climate change & Forcing estimate purpose

Aerosol model evaluation purpose

11/4/07


Size-resolved Microphysics

• TOMAS (TwO-Moment Aerosol Sectional microphysics algorithm)[Adams and Seinfeld, 2002]

– Moments = 1) aerosol number and 2) aerosol mass– 30 bins segregated by dry mass per particle– Size range is about 10 nm – 10 μm

N1 N2 N3

N4 N5N6 N7

N30SO4

2-

NaCl

…

Size Distribution

Dp

…SO42-

NaCl

11/4/07


TOMAS processes

–Coagulation–Condensation/ evaporation–Nucleation– In-cloud sulfur oxidation–Size-resolved dry deposition–Size-resolved wet deposition

11/4/07


TOMAS Status

• Species: Number, SO42-, Sea-salt

• Advection– Problem: TPCORE/ PPM parabolic

interpolation artificially grows/shrinks particles – Fixed (see me for detail)

• Convection– Negative entrainment at some time steps

11/4/07


TOMAS Status

• Emission– Sulfate: Same total, apply size distribution– Sea-salt: Clarke et al (2006) parameterization– Number: calculated from emitted mass and

assumed size distribution

• Nucleation : Binary nucleation (H2SO4-H2O)

• Aqueous oxidation of sulfate– Distribute over activated size range using

condensation/evaporation algorithm

11/4/07


TOMAS Status

• Wet deposition– In-cloud:

• Activated particles are removed same way as the original rainout (1st order loss).

• Interstitial particles are assumed inert.– Below-cloud: Apply size-resolved washout rate

11/4/07


TOMAS Status

• Dry deposition– Size-resolved scheme of Zhang et al (2001) as

in later versions of G-C

0.01 0.1 1 10

Dry particle diameter (m)

10

1

0.1

0.01

Deposition Velocity (cm s-1)

Original

New

11/4/07


Aerosol Prediction from TOMAS

11/4/07


Model ResultsTotal Number Concentration (cm-3)

11/4/07


Model Results

Total Number Concentration (cm-3)

CCN(0.2%) (cm-3)Notice the

scale!

11/4/07


Model Results

Total Number Concentration (cm-3) CCN(0.2%) (cm-3)

Latitude Latitude

Pre

ssur

e [m

bar]

Nucleation region

Heavy pollution region

Tropical convection CCN removed with rain

Emitted as well as grown into CCN sizes

11/4/07


Model Results

Number Size DistributiondN/dLogDp (cm-3)

Industrial region, China

Sea-salt emission-Significant mass (Larger particle)-Fewer numbers.

Nucleated particles

Grow by condensation as they descend

Cloud processingFrom cloud top down to surface Bimodal dist.

Sulfate primary emission

Remote marine, Southern Ocean

11/4/07


Model Results

Number Size DistributiondN/dLogDp (cm-3)

Remote marine, Southern Ocean

L19

L17

L10

L1

11/4/07


Upcoming Tasks & Challenges

• Introducing 30-bin OC, EC, and dust

• Running 2x2.5 memory need for (30*(n+2)) aerosol tracers, where n=number of mass species

• OR … Running nested grid over ACE-Asia domain?

• Comparing aerosol prediction with number size distribution measured from ACE-Asia

11/4/07


Question?

Check out my poster about …

• Comparison with Heintzenberg marine aerosol data

• Inter-model comparison :

G-C, GISS GCM-II’ and GLOMAP

implementation of sulfate and sea-salt aerosol microphysics in geos-chem win trivitayanurak &...

Documents

aerosol number

microphysics tomas

aerosol mass

seasalt aerosol microphysics

aerosol prediction

tomas slide

aerosol microphysics

implementation of sulfate