This is a partial reconstruction of the original project report.
Dry deposition is an important sink for pollutants and consequently
it plays an important role in the formulation of the lower
boundary condition in photochemical and pollution transport models.
Because dry deposition is important for modeling purposes, the
California Air Resources Board sponsored a large field program
in July and August of 1991 to study the dry deposition
of ozone in the San Joaquin Valley. This field experiment,called the
California Ozone Deposition Experiment (CODE)
is part of the larger San Joaquin Valley Air Quality Study.
CODE was designed to provide information on the nature of the physical
and biological processes governing the dry deposition of ozone
in the San Joaquin Valley and for developing
and evaluating air quality models for that region.
Synopsis of Field Phase
The San Joaquin Valley Air Quality Study (SJVAQS) ASTER deployment
was sponsored by the California Air Resources Board of the
state of California to quantify the ozone deposition flux
to crop vegetation and served to produce imput data for the air quality
models used for regulatory purposes.
Bill Massman and Larry Marht were the principal investigators and
Jim Pederson was the contact manager for the CARB. Tony Delany
was the ASTER scientist and Steve Semmer the ASTER engineer.
Tom Horst, Steve Oncley and Charlie Martin were involved
in the ASTER research.
In addition to the ASTER cotton field investigation
two other ground based surface flux facilities were deployed;
the Environment Canada facility (Gerry den Hartog)
in a raisin grape vinyard, and
the University of California at Davis
(Roger Shaw) in a dry grass field. The
Environment Canada instrumented Twin Otter aircraft (Ian McPherson)
overflew all sites.
Sonoma Tech, a consulting firm, was responsible for site preparation.
Prior to the field phase a planning meeting was held at the office
of the CARB in Sacramento. Tony Delany attended and made preliminary
arrangements as to site requirements. The general location of the research
site was determined by Ian McPherson and Paul Hanson of Sonoma Tech.
Tom Horst and Steve Semmer made a site visit to check the micrometeorological
validity of the site and the logistics for the deployment.
The truck containing the field-ware and the single ASTER seatainer arrived
at the site 25 June 1991 and the walk-ways, towers, power and data cabling
was laid out. Some postponement was involved due
to a delay in the installation of the power drop. The sensor installation
was completed by 7 July 1991 and the system was operational
on 11 July 1991.
A rental trailer required for the PG and E monitors, the suppies for
the pilot balloon system operated by Fresno State College, and
the contents of the ASTER second seatainer was positioned south
of the ASTER seatainer. The NOAA WPL mini-sodar was south of the
PG and E trailer.
Operations were continuous from 11 July to 7 August (JD 192 - JD 219) 1991.
Tear-down and repacking of the trailers occupied a four day period.
The ASTER site was located
80 km west of Fresno in the central valley of California.
Maps 1 and 2 show the location of the site relative to urban areas
and the major highways.
Maps 3 and 4 illustrate that the facilty was situated in an extremely
open flat agricultural area of cotton, tomatoes, melons and beans
with very few obstructions and with access roads and irrigation canals
on the section or quarter section boundaries.
A skyline survey indicates the scacity of nearby obstructions.
The tower array was erected 150 m from the eastern edge of a cotton field.
The site plan illustrates the relative positioning of the
five towers, the radiation array, the instrument shelters and the
Of particular note is the exhaust for the fast ozone sensor vacuum pump.
Under the prevailing meteorological conditions the NOX laced
exhaust was emitted
down-wind of the ASTER array and sufficiently cross-wind
from the PG and E that it was not sensed. However
during quiescent nighttime conditions the exhaust spread across the site
and represented a problem.
The site plan and the sensor configuration diagram show the arrangement of the
meteorological, chemical, and radiation instruments. The soil
temperature and heat flux sensors were located near the dark-horse, the 4m
stand upon which the radiation sensors were mounted. The
soil sensors were distributed such that both ridge and furrow were
represented. Samples were taken each day from both ridge and furrow
to measure the gravitational soil moisture.
Near Firebaugh, California (36 deg 48' 50"N, 120 deg 40' 38"W).
A table of sensors is available.
Daily weather plots were included in the original project report, but are
not currently online.
The 5-minute average statistics in NetCDF format are
A compendium of various formulae and constants