Regional Modeling Joseph Cassmassi South Coast Air Quality Management District USA

Regional Modeling Applications Determine a “carrying capacity” for a region Provides a view of current, past and future air quality Planning tool to develop a long term control strategy

Expectations vs. Limitations Performance of regional models is as good as the worst component In data rich environments modeling errors range between 15-50% Requires a significant investment --data --man hours --computation resources

Modeling Overview Goal or purpose Conceptual model Model selection Define modeling domain Emissions inventory Air quality and meteorological data Define an episode for model application

Conceptual Model Understanding of the overall picture --extent of data availability --confidence in the data --processes that are contributing to the observed air quality Meteorological and air quality description of the episode Understanding of why the episode stands apart from normal or average conditions

Model Selection Air quality --platform (dedicated or family) --chemistry module --dispersion Meteorological --objective analysis --diagnosticanalysis --prognostic models

Modeling Domain Regional approach --focus on Delhi? -- up and down wind areas (from the conceptual model) Meteorological modeling domain may be greater than the air quality domain Grid scales may be different Need accurate terrain file

General Data Requirements Data required is domain dependent --size --complexity of terrain --pollutant sensitive Levels of model applications --limited surface and upper air --moderately dense surface and multiple upper air --intensive field study

Air Quality Data Requirements Surface --routine air quality monitoring --chemical speciation` --define boundaries/initialization Upper air --boundaries/initialization --transport

Meteorological Data Requirements Surface --winds, temperature, humidity --insolation and cloud cover Upper Air --winds, temperature, moisture --lapse rates and stability --mixing heights

Southern California Monitoring Air Quality Monitoring ambient monitoring sites sites speciated data --upper air characterization - as needed Meteorology monitoring or reporting sites --5 sounding/aircraft sites --10radar profilers/sounders

Delhi Monitoring ~ 6-10 air monitoring sites --fixed& mobile vans --representative of high traffic areas --limited speciation Surface meteorological at air monitoring locations Twice daily soundings: Delhi, Gwalior, Jodhpur

Emissions Gridded emissions inventory --point --mobile --area Day specific Allocation factor/surrogates Temporal profile Weekdays vs. weekends

Applications: Episode Selection Data Availability --meteorology --air quality --boundary conditions Episode severity Representative of problem Field study data available

Delhi Profile Reasonably flat terrain Upper air --limited upper air meteorology may characterize domain Surface meteorology --river valleys will channel winds --urban heat island --Great Indian Desert --need additional monitoring

Delhi Profile (continued) Ambient air quality monitoring --may not characterize regional issue --need to characterize background profile --identify locations of maximum pollution impact

Recommendations Meteorology --enhance surface network --consider upper air profiling Air quality --enhance network --speciation profiles --characterize boundaries Investigate potential for field study --PM - fall, Ozone - late spring