Research Projects

Project at a Glance

Project Status: complete

Title: Sierra cooperative ozone impact study: year 2--volume 1.

Principal Investigator / Author(s): Carroll, John J

Contractor: UC Davis

Contract Number: A032-129


Research Program Area: Ecosystem & Multimedia Effects, Atmospheric Processes

Topic Areas: Acid Deposition, Area Sources, Ecosystem Impacts, Field Studies, Impacts, Monitoring


Abstract:

The purpose of the Sierra Cooperative Ozone Impact Assessment Study (SCOIAS) is the document the degree to which sensitive pine species in Sierran forest are exposed to ozone and the amount of damage the exposed trees exhibit. The major cooperators are the U.S. Forest Service (USFS), the California Air Resources Board (ARB) and the University of California, Davis (UCD). This document reports progress made by the UCD cooperations during the second year of the project (June 7, 1991 to June 6, 1992). The major tasks performed were the continued operation of the five sites established in the first year's effort, the installation and operation of a sixth site and data quality control, analysis and archiving. The five stations established in 1990 are Mountain Home within the Sequoia, Jerseydale in the Sierra, Five - Mile Learning Center in the Stanislaus, Sly Park Learning Center in the El Dorado and White Cloud in the Tahoe National Forests. The sixth site was installed at Shaver Lake in the Sierra National Forest and was activated on July 24, 1991. Instrumentation to measure solar radiation was added to all sites between August 28 and September 19, 1991. The ozone monitoring season is the warm part of the year, from about April 15 to October 15, although actual station operating dates depend on accessibility in the spring. At all but one site, the targeted 80% data coverage was attained or exceeded. At one site a combination of computer system problems and ozone monitor malfunctions caused data voids totaling 22% of the operational period. These problems appear to have been solved by mid-season. Measured ozone concentrations are typically highest in the afternoon hours, and tend to increase toward the southern end of the network. Stations located on well defined steep slopes show a very strong diurnal variation in ozone concentration and meteorological conditions. Hourly peak ozone concentrations from June through September are greater than 60 ppbv at all sites nearly every day, in excess of 80 ppbv at most sites more than half the days and in excess of 100 ppbv at least several days a month at all sites and nearly half the days at the most impacted site (Mountain Home).


 

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