(Impacts are Felt on Scales from Local to Global)

Aerosols Link Climate, Air Quality, and Health: Dirtier Air and a Dimmer

Sun

Emissions

Impacts

==

Lifecycle of Particles in the Atmosphere

Some particles are emitted directly (e.g., dust, black carbon), while others are formed as result of atmospheric chemistry (sulfate)

Some emissions are due to natural process (e.g., sea salt), others due to anthropogenic activities (e.g., black carbon from coal combustion).

Models Play a Critical Role in Linking Emissions to Aerosol Distributions and Subsequent Effects

Modeled

Observed

Aerosols and climate and air quality share: common emissions; common models; and synergistic control/policy strategies

Predicting Aerosol Distributions Have Added Complexities Of Emissions And Chemistry,

And

Size And Composition Matter!

Maldives

SSASub-micron

Super

Size:

Data: ABC Project

South Asia

Aerosol Composition

Linking Emissions to Aerosol Distributions and Subsequent Effects

• How good are the models?

• What is the consistency of model-derived information? How model dependent are the results?

• How uncertain are the model predictions?

• What do the observations tell us about the quality of the calculation?

The Emission Estimates for Particles are Represent the Largest Source Of Uncertain

Energy-related

Open Burning

BC

Important – the lifetime of aerosols in the atmosphere is on the order of days, while that for CO2 is many decades

3.2 Tg/yr

5.8 Tg/yr~25% biofuels

% Uncertainty in Emissions

Model Intercomparison Studies Provide Valuable Information on Diversity of Model-Derived Information

Does low diversity reflect scientific understanding or simply consensus?

Textor et al., ACP, Atmos. Chem. Phys. Discuss., 5, 8331–8420, 2005

Comparison of 16 Global

Aerosol Models

Hanimadhoo Black Carbon Measurements

-0.10

0.10

0.30

0.50

0.70

0.90

1.10

1.30

1.50

9/1 10/1 10/31 11/30 12/30 1/29 2/28 3/30 4/29 5/29 6/28 7/28 8/27

JDT (2004-2005)

ug

/m3

EC PM 1.0

EC PM2.5

STEM-TRACER-RunE

Black carbon at the Maldives

Observed

Modeled

Predicted Surface Black Carbon Concentrations

Despite High Uncertainty Current Models Have Significant Predictive Capabilities

Data: ABC Project

Linking Aerosol Distributions to Radiative Effects

Dust

Nss Sulfate

Organics

Sea Salt

Black Carbon

Adding Observational Constraints Reduces Uncertainty

The Effect On Calculated AOD When Using Observational Parameterizations For Optical Properties Can Be Large

Observations based on field experiments (in situ data)

Bates et al., ACPD, 2006

A p

riori

Constrained

Combining Satellite with Models Provides Improved Fields for Analysis

How to optimally adjust individual aerosol quantities given AOD (sulfate, BC, OC, dust, sea salt)?

- AOD by itself not unique

- Fine mode fraction helps – allows sulfate, black carbon and organic carbon to be modified separately from dust and sea salt

Apriori AOD Model Prediction

AOD MODIS+AERONET AOD ADJUSTED MODEL

Total Fine-fraction

Combining Satellite and Surface Measurements with Models Provides Improved Fields for Analysis

How to optimally adjust individual aerosol quantities given AOD (sulfate, BC, OC, dust, sea salt)?

- AOD by itself not unique

- Fine mode fraction helps – allows sulfate, black carbon and organic carbon to be modified separately from dust and sea salt

- SSA gives info to adjust absorption vs scattering – adjust black carbon separately from sulfate and organic carbonAOD MODIS+AERONET

Total Fine-fraction

Maldives

We need more surface observations! (for validation)

Reductions Of Uncertainties When Measurements Are Used To Inform The Models

Normalized uncertainties (uncertainty range of the indicated quantity divided by the value of the quantity)

DRE: Direct radiative effect (all aerosols)

DCF: Direct climate forcing (that portion due to anthropogenic aerosols)

Bates et al., ACPD, 2006

Where do we go from here?Changes in China Emissions from 2001-2006

Due to Energy Growth and Improved MethodologySO2:  +44%NOx:  +65%CO:  +57%VOC: +51%BC:  +92%OC:  +17%

1993 2003

Hong Kong

Guangzhou

Another Twist to the

Intercontinental Pollution Issue

Development indicated by red and blue

50% higher than if done in the West !!

Streets et al., ES&T, 2006

Heald et al., JGR, doi:10.1029/2005JD006847, 2006

(Emissions due to exports in PRD can be offset at an annual cost of $250 million, or 0.3% of total exports value)

Emissions Due To Exports Have Significant Local Health/Climate Impacts AND They Contribute To Impacts in North America As Well!

MODIS AOD Asia Contribution

Asia Contribution

Linking Emissions to Aerosol Distributions and Subsequent Effects -- Summary

Models play an essential role.

Models have improved substantially.

Further improvements will require reductions in key uncertainties (e.g., emissions, better basic understanding of some processes).

Closer integration of observations.

Air quality and climate

linkage offers synergistic policy/actions.

In the LMD-Z model, the change in net outgoingshortwave radiation in going from experiment 3 to experiment4 is somewhat larger (−0.47Wm−2) than it is ingoing from experiment 4 to experiment 5 (−0.29Wm−2) butthe change between experiment 4 and experiment 5 is stillsignificant relative to the other changes introduced in theseexperiments. These changes are caused by large changes inthe change in droplet concentrations (Fig. 3b) between thepresent day and pre-industrial simulations for experiment 5compared to experiment 4, which are simply due to the largechanges in present day and pre-industrial aerosols calculatedby each of the models. Thus, within any one model, thechange in net outgoing shortwave radiation is most sensitiveto the calculation of individual aerosol fields than to anyof the other parameters in the cloud scheme.