Central California Ozone Study (CCOS) - Desert Research Institute

CCOS Field Operations Plan Version 2: 5/31/00
Understanding the response of ozone levels to specific changes in VOC or NOx
emissions is a fundamental prerequisite to developing a cost-effective ozone abatement strategy.
The varying emissions that occur between weekday and weekend periods provide a natural test
case for air quality simulation models. At the same time, the model performance and evaluation
must be accompanied by an evaluation of the accuracy of the temporal and spatial patterns of
precursor emissions. With the questions that still remain regarding the accuracy of emission
inventories, the “weekend effect” emphasizes the need for observation-based data analysis to
examine the relationship between ambient O3 and precursor emissions. The results of
corroborative data analyses need to be reconciled with model outputs taking into consideration
the various sources of uncertainties associated with both approaches.
The current conceptual model will be revisited and refined using the results yielded by
the foregoing data analyses. New phenomena, if they are observed, must be conceptualized so
that a mathematical model to describe them may be formulated and tested. The formulation,
assumptions, and parameters in mathematical modules that will be included in the integrated air
quality model will be examined with respect to their consistency with reality.
1.2 Technical Objectives
The study design and experimental approach for CCOS are defined in terms of specific
technical objectives. A number of tasks are required to meet each of the technical objectives.
These tasks are listed in this section and are described in greater detail in Sections 3 and 4 of the
field study plan (Fujita et al., 1999).
Preparation, Execution and Evaluation of Air Quality Simulation Modeling Systems (M)
Objective M-1. Apply air quality models for the attainment demonstration portion of the SIP for
the proposed 8-hour and state 1-hour ozone standards.
a. Select the most suitable modeling systems (for meteorology, emissions, and air quality)
for representing photochemical air pollution in central and northern California. At least
one of the models selected should have the ability to simulate both ozone and fine
particles. Simulations with that model could be applied to both CRPAQS and CCOS.
This will facilitate integration of results across both studies.
b. Analyze the data collected during the CCOS field measurement program and select a
minimum of three ozone episodes to simulate.
c. Specify model domain boundaries, boundary conditions, initial conditions, chemical
mechanisms, aerosol module, plume-in-grid module, grid sizes, layers, and surface
characteristics.
d. Identify performance evaluation methods and performance measures, and specify
methods by which these will be applied.
e. Evaluate the results of the meteorological model.
Chapter 1: INTRODUCTION 1-5