CONCEPTUAL MODELING PROTOCOL

FOR THE NEIGHBORHOOD

ASSESSMENT PROGRAM

Objectives of Modeling Protocol

develop and evaluate methodologies to estimate annual average concentrations of various pollutants released from multiple sources at the neighborhood scale (Barrio Logan)

recommend a method to perform neighborhood assessments

Size of Modeling Domain

Micro-scale (Neighborhood scale) modeling - receptors located near emission sources, i.e., meters to few kilometers from the sources

Regional scale modeling - source and receptor distances of several kilometers, to hundreds of kilometers, to the size of air basins

Air Toxic Pollutants To Be Modeled Micro-scale modeling - more than 100 pollutants,

including:Acetaldehyde, Acrolein, Acrylonitrile, Arsenic, Benzene, Beryllium, 1,3-Butadiene, Cadmium, Chloroform, Hexavalent Chromium, Ethylene Dibromide, Dioxin, Diesel PM, Formaldehyde, Hydrazine, Lead, Manganese, Methylene Chloride, Mercury, Nickel, (PCBs), Perchloroethylene, Trichloroethylene, Vinyl Chloride

Regional modeling - 30 pollutants:Acetaldehyde, Acrolein, Arsenic, Benzene, Beryllium, 1,3-Butadiene, Cadmium, Carbon Tetrachloride, Chloroform, Diesel PM, Ethylene Dichloride, Ethylene Oxide, Formaldehyde, Hexavalent Chromium, Iron, Lead, Manganese, Mercury, Methylene Chloride, MTBE, Nickel, o-Dichlorobenzene, p-Dichlorobenzene, Perchloroethylene, Styrene, Toluene, Trichloroethylene, Vinyl Chloride, Xylenes, Zinc

Micro-scale Models to Estimate

Annual Concentrations Traditional Models

ISCST3 - U.S. EPA regulatory model CALINE - U.S. EPA approved model for line sources

Advanced Models AERMOD - recommended as replacement for ISCST3 CALPUFF- recommended model for complex terrain and

for long-range transport

New and Emerging Models Lagrangian particle dispersion model - state-of-the-science

short-range model that estimates concentrations at scales of meters to tens of meters from a source

Input Data For Micro-scale Modeling

meteorology (hourly surface observations from local airports and on-site measurements)

point source emissions (including some traditional “area wide” sources, e.g. dry cleaners)

mobile source emissions (hourly traffic volumes and emission factors)

source configurations (e.g., stack heights)

receptor locations

Micro-scale Modeling Domain - Mobile Sources

Micro-scale Modeling Domain - Point Sources

Regional Models To Estimate

Annual Concentrations

Traditional Models

UAM (Urban Airshed Model) - used for air quality planning

Advanced Models

Models-3 - state-of-science model developed by U.S. EPA

Regional Scale Modeling Objective: Estimate annual concentrations due to transport of pollutants from

distant sources or air basin(s) that contribute to neighborhood areas (background concentrations)

Improvements to Regional Scale Modeling:

Incorporate SAPRC 99 and air toxic chemistry

Apply over air basin(s) using an entire year of data for meteorology and emissions

Inputs For Regional Scale Modeling

Development of Regional Emissions Inventory

Update the 1998 database to reflect seasonal variations in emissions and update toxic emissions as well

Utilize latest version of EMFAC2000 to estimate motor vehicle emissions

Development of Meteorological Inputs for Regional Air Quality Models

CALMET - a diagnostic model that requires observational data for winds and temperature

MM5 - an advanced state-of-science prognostic meteorological model to simulate winds and temperatures

Location of the coarse and fine grids used in MM5 model

CALMET - Wind Fields (Morning)

300 350 400 450 500 550

3600

3650

3700

3750

3800

-10005010015020040060080010001200140016001800200022002400260028003000

Barrio-Logan R egional m odeling dom ain .W ind vector at hour 04 on 01/01/1998 Layer 1 (10 m ).

UTM X (km )

UT

M Y

(km

)

C :|barrio |reg ional|ca lpuff|ca lm et|p rtm et|v001h04L1.srf

scale: 1 .5 m /s per 0 .1 in

CALMET -

Wind Fields

(Afternoon)

300 350 400 450 500 550

3600

3650

3700

3750

3800

-10005010015020040060080010001200140016001800200022002400260028003000

Barrio-Logan R egional m odeling dom ain .W ind vector at hour 16 on 01/01/1998 Layer 1 (10 m ).

UTM X (km )

UT

M Y

(km

)

C :|barrio |reg ional|ca lpuff|ca lm et|p rtm et|v001h16L1.srf

scale: 1 .5 m /s per 0 .1 in

MM5 - Wind Fields (Afternoon)

Regional scale air quality modeling domain

Model Performance Evaluation A scientific process to ensure models are working

properly and are estimating reliable concentrations Compare model estimates of concentrations with

observational data and conduct operational and diagnostic evaluation

Follow the procedures identified in ARB's Technical Guidance Document on modeling.

Standard statistical techniques such as bias and gross error will be calculated for annual model estimates of concentrations as well as for monthly and seasonal averaging times

Databases For Evaluating Model Performance

Micro-scale models:

Conduct a field monitoring study to collect a database for short-range dispersion in urban neighborhood areas

Field study includes release of a tracer gas, bag sampling and continuous monitoring of the tracer gas, and meteorological measurements which include six sonic anemometers and a mini-sodar

Sampling will be conducted over a one week period for four seasons of year at several sites

Funding available for total of 20 weeks of sampling

Databases For Evaluating Model Performance

Regional Models:

Use routine meteorological and air quality (criteria and toxic) data collected by air districts and ARB

Utilize data collected from recent studies (SCOS97 and CRPAQS/CCOS) and other data gathered from special monitoring studies

Recommendations From Study

Identify which micro-scale and regional models are best suited for assessing neighborhood impacts

Develop recommendations for guidelines to determine the cumulative impacts posed by air pollutants at the neighborhood-scale

Share modeling results and recommendations with U.S. EPA and other interested groups