Central California Ozone Study (CCOS) - Desert Research Institute

CCOS Field Operations Plan Version 2: 5/31/00
2.0 CCOS FIELD MEASUREMENTS
Data requirements for CCOS are determined by the need to drive and evaluate the
performance of modeling systems, which include three components. A meteorological model
provides winds fields, vertical profiles of temperature and humidity, and other physical
parameters in a gridded structure. Emissions inventory and supporting models provide gridded
emissions for anthropogenic area and point sources and natural emissions. An air quality model
simulates the chemical and physical processes involved in the formation and accumulation of
ozone. In evaluating modeling system performance, the primary concern is replicating the
physical and chemical processes associated with actual ozone episodes. This necessitates the
collection of suitable meteorological, emissions, and air quality data that pertain to these
episodes. The data requirements of CCOS are also driven by a need for complementary,
independent and corroborative data analysis so that modeling results can be compared to current
conceptual understanding of the phenomena replicated by the model.
2.1 Geographic Scope
Central California is a complex region for air pollution, owing to its proximity to the
Pacific Ocean, its diversity of climates, and its complex terrain. Figure 2.1.1 show the overall
study domain with major landmarks, mountains and passes. The CCOS domain includes most of
northern California and all of central California. The northern boundary extends north of
Redding and provides representation of the entire Central Valley of California. The western
boundary extends approximately 200 km west of San Francisco and allows the meteorological
model to use mid-oceanic values for boundary conditions. The southern boundary extends below
Santa Barbara and into the South Coast Air Basin. The eastern boundary extends past Barstow
and includes a large part of the Mojave Desert and all of the southern Sierra Nevada. The Bay
Area, southern Sacramento Valley, San Joaquin Valley, central portion of the Mountain Counties
Air Basin (MCAB), and the Mojave Desert are currently classified as nonattainment for the
federal 1-hour ozone NAS. With the exception of Plumas and Sierra Counties in the MCAB,
Lake County, and the North Coast, the entire study domain is currently nonattainment for the
state 1-hour ozone standard. The Mojave Desert inherits poor air quality generated in the other
parts of central and southern California.
2.2 Study Period
The CCOS field measurement program will be conducted during a four-month period
from 6/1/00 to 9/30/00. A network of upper-air meteorological monitoring stations will
supplement the existing routine meteorological and air quality monitoring network in order to
identify and characterize meteorological conditions that are conducive to ozone formation during
this four-month period. Supplemental air quality measurements will be made during a threemonth
period from 6/15/00 to 9/15/00 (study period), which corresponds to the majority of
elevated ozone levels observed in northern and central California during previous years.
Continuous surface and upper-air meteorological measurements and surface air quality
Chapter 2: FIELD MEASUREMENTS 2-1