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An evaluation of the regional acid deposition model surface module for ozone uptake at three sites in the San Joaquin Valley of CaliforniaPlants and soils act as major sinks for the destruction of tropospheric ozone, especially during daylight hours when plant stomata open and are thought to provide the dominant pathway for the uptake of ozone. The present study, part of the California Ozone Deposition Experiment, compares predictions of the regional acid deposition model ozone surface conductance module with surface conductance data derived from eddy covariance measurements of ozone flux taken at a grape, a cotton, and a grassland site in the San Joaquin Valley of California during the summer of 1991. Results indicate that the model (which was developed to provide long-term large-area estimates for the eastern United States) significantly overpredicts the surface conductance at all times of the day for at least two important types of plant cover of the San Joaquin Valley and that it incorrectly partitions the ozone flux between transpiring and nontranspiring components of the surface at the third site. Consequently, the model either overpredicts or inaccurately represents the observed deposition velocities. Other results indicate that the presence of dew does not reduce the rate of ozone deposition, contradicting to model assumptions, and that model assumptions involving the dependency of stomata upon environmental temperature are unnecessary. The effects of measurement errors and biases, arising from the presence of the roughness sublayer and possible photochemical reactions, are also discussed. A simpler model for ozone surface deposition (at least for the San Joaquin Valley) is proposed and evaluated.
Document ID
19950029710
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Massman, W. J.
(U. S. Dept. of Agriculture/Forest Service, Fort Collins, CO United States)
Pederson, J.
(California Air Resources Board, Sacramento, CA United States)
Delany, A.
(National Center for Atmospheric Research, Boulder, CO United States)
Grantz, D.
(Univ. of California, Parlier, CA United States)
Hertog, G. Den
(Atmospheric Environment Service Downsview, Ontairo, Canada)
Neumann, H. H.
(Atmospheric Environment Service Downsview, Ontairo, Canada)
Oncley, S. P.
(National Center for Atmospheric Research, Boulder, CO United States)
Pearson, R., Jr.
(NASA Ames Research Center Moffett Field, CA, United States)
Shaw, R. H.
(Univ. of California, Davis, CA United States)
Date Acquired
August 16, 2013
Publication Date
April 20, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: D4
ISSN: 0148-0227
Subject Category
Environment Pollution
Accession Number
95A61309
Distribution Limits
Public
Copyright
Other

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