Image D. Anderson, NASA, from Seinfeld et al., BAMS, in press, 2003

Intercontinental Transport of Pollutants Out & Into Asia (emphasis on particles)

Intercontinental Transport of Pollutants Out & Into Asia

• What do we know about the transport mechanisms?

• How good are the models?

• What are the sources of uncertainty?

• What do the observations tell us?

• What are some next steps?

The CFORS forecast (upper left) of the two dust systems are shown above. The dust plume (pink) represents the region with dust concentrations greater than 200 grams/m3. White indicates clouds. The SeaWifs satellite image (upper right) also clearly shows the accumulation of dust spiraling into the Low Pressure center. Also note the strong outflow of dust in the warm sector “ahead” of the front over the Japan Sea. The two systems are clearly seen in the satellite derived TOMS-AI (aerosol index) (lower right). The dust event is clearly seen in the China SEPA air pollution monitoring network. Lower left hand panel shows extremely large ground level concentrations (http://www.ess.uci.edu/~oliver/tracep/airqual/index.html). The sandstorm and sand-drifting weather, which swept across most parts of China caused severe visibility and air quality problems

http://news.xinhuanet.com/english/20010409/395181.htm

NASA-Seawifs

• Convection

• Warm conveyor belt lifting

• Post-frontal boundary layer transport

• Low level pre-frontal

• Advection in the westerlies

• Cold front subsidence

• Large-scale subsidence

• Mountain wave subsidence

• Boundary layer transport

Transport Mechanisms: As informed by field experiments & models (e.g., Trace-P, Ace Asia, ITCT-2k2/Peace,

ICARTT, ABC)

Liang et al., JGR, 2004

Convection 8% of time accounts for ~35% of outflow flux

Oshima et al.,JGR, 2004

Example: Results from Peace/ITCT2K2

One Model’s View: One Spring

Dust

Sulfate

BC

Transport to Asia

viz. Newell and Evans [2000]

100°E

Wild, et al., 2004

How Good Are the Models?

Model inter-comparison studies focused on Asia: e.g., MICS-Asia, DMIP, Trace-P/Ace-Asia

Comparisons of predictions with observations

Sulfate concentration in March 2001 (g m-3)

contents

Model-1 Model-3 Model-4

Model-5 Model-6 Model-7 Model-8

Model-2

MICS Phase II Results: Concentrations agree better than deposition fluxes

http://www.adorc.gr.jp/adorc/mics.html

DMIPS: Dust inter-comparison study

Spread in mean vertical profiles

Uno et al., 2005

Receptor 7 - Oki (Japan)

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7 8

Model Intercomparison Study (MICS) Asia:

Source/Receptor Predictions

http://www.adorc.gr.jp/adorc/mics.html

Receptor 17 - Taichung (Taiwan)

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6 7 8

What are the Major Sources of Uncertainty in the Calculation of Aerosol Export?

0%

100%

200%

300%

400%

500%

600%

700%

800%

900%

China Japan Other EastAsia

SoutheastAsia

India OtherSouth Asia

Ships All Asia

(95%

Con

fiden

ce In

terva

l,

? )SO2

NOx

CO2

CO

CH4

VOC

BC

OC

NH3

Streets et al., JGR, 2003

Emissions

Predictions of wet deposition are markedly

different

Impact of Wet Removal on Predicted BC

Progress limited by lack of understanding and observations

Removal Processes Remain Poorly Characterized in Models

Emissions Wet

removal Chemical

Formation Vertical

Transport Model

Resolution Total

nss SO4 0.3 0.3 0.3 0.5 0.1 0.7

BC 3 1 -- 0.5 0.1 3.2

OC 3 1 3 0.5 0.1 4.3 Dust 5 1 -- 0.5 1 5.2

Sea Salt 5 0.3 -- 0.5 1 5.13

Summary of Major Sources of Uncertainty in the Calculations

Summary of estimated relative uncertainties* for integrated aerosol quantities (column amounts, fluxes)

*(uncertainty divided by mean value).

Note: for analysis of specific points some of these terms are larger…

How do the models perform with respect to observations?

BC

Sulfate Obs

M

Comparison of Predictions vs Obs for INDOEX and Ace-Asia (Ron Brown ship data)

Sub-micron Super-micron Total

Mass

Composition

Comparison of Observed and Predicted Chemical composition

(sub-micron mode)

0.0001

0.001

0.01

0.1

1

10

100

Export of Particles: One Model’s View -- One Spring

Models predict a larger fraction of BC & OC (wrt sulfate) is

transported out of Asia

What do the observations tell us?

Model-based Observation-based

~40% exported

Koike et al., JGR, 2003

Both approaches have large uncertainties !!

40%

Ace Asia Aerosol Column Means: Summary of Uncertainty, Model to Model Variability, and

Predictability (NOAA CCSP, ABC)

2 Models: MOZART

STEM

Final thoughts

Analysis is highly uncertain due to understanding, current state of models, inputs and available observations.

Presently observations are used to compare with predictions --- good for process development, confidence building.

Observations by themselves can not provide the answer -- models necessary …. but also can’t do it alone.

Improved understanding needed to reduce uncertainty: Processes (deposition) Role of clouds (transport & removal) Emissions

Expanded Monitoring Activities Will Provide Valuable new InformationExpanded Monitoring Activities Will Provide Valuable new Information EANET EANET ABCABC

Final thoughts (cont)

Enhanced measurements (systems and experimental designs) needed to constrain the problem

Final thoughts (cont) Integration of measurements and models needed…ensemble

and data assimilation (get uncertainies, inversion for emissions and removal parameters, etc.)

Amir et al., JGR 2005

McKeen et al., in

prep.