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/m 3. 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 ( The sandstorm and sand-drifting weather, which swept across most parts of China caused severe visibility and air quality problems 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-1Model-3Model-4 Model-5Model-6Model-7Model-8 Model-2 MICS Phase II Results: Concentrations agree better than deposition fluxes

DMIPS: Dust inter-comparison study Spread in mean vertical profiles Uno et al., 2005

Model Intercomparison Study (MICS) Asia: Source/Receptor Predictions

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

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 SulfateObs M

Comparison of Predictions vs Obs for INDOEX and Ace-Asia (Ron Brown ship data) Sub-micronSuper-micronTotal MassMass CompositionComposition

Comparison of Observed and Predicted Chemical composition (sub-micron mode)

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-basedObservation-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 Information EANET ABC 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.