Alex Vermeulen
Manager
Seasonal variability of ozone dry deposition under southern European climate conditions, in Portugal
Author
Summary, in English
Ozone dry deposition measurements were carried out during approximately one year over a flat grass field in Portugal. The results show prominent diurnal and seasonal patterns in deposition flux, dry deposition velocity and surface resistance, especially for the daytime period. Dry deposition velocities vary diurnally from a minimum of 0.1 cm s(-1) during the night to a maximum of 0.7-0.5 cm s(-1) during the day. The observed canopy resistance (R-c) varies from values higher than 500 s m(-1), at night, to a minimum of 200 s m(-1), around noon. Seasonal variation is characterised by daytime R-c values much larger in summer than in winter and spring, while nighttime values do not show any evident seasonal pattern. This behaviour can be ascribed to the stomatal intake, which represents the most important controlling factor on ozone dry deposition. The Wesely parameterisation scheme of surface resistance predicts R-c diurnal cycles reasonably well. However, the observed canopy resistance seasonal cycle is completely different from Wesely predictions, since season parameters in Wesely's parameterisation were defined for a vegetation growing cycle different from that prevailing in our conditions. (C) 1999 Elsevier Science Ltd. All rights:reserved.
Publishing year
2000
Language
English
Pages
195-205
Publication/Series
Atmospheric Environment
Volume
34
Issue
2
Document type
Journal article
Publisher
Elsevier
Topic
- Meteorology and Atmospheric Sciences
Keywords
- ozone dry deposition
- surface resistance
- stomatal resistance
- diurnal
- variation and parameterisation
Status
Published
ISBN/ISSN/Other
- ISSN: 1352-2310