Seasonal and spatial variations in natural volatile organic compound emissions

Atmospheric concentrations of ozone and other air pollutants, in some regions, are sensitive to surface fluxes of volatile organic compounds (VOCs). Plant foliage is the source of at least half of all VOC emissions in the United States and more than two-thirds of global VOC emissions. Observed spatial and seasonal variations in foliar VOC emissions range over several orders of magnitude. Land characteristics data are an important component of the modeling techniques used to estimate VOC emission rate variations due to seasonal and spatial changes in species composition, foliar density, and other factors. Model techniques and land characteristics databases are compared and evaluated in this paper. Significant differences in VOC fluxes are predicted depending on spatial resolution, procedures used to develop land characteristics databases, and foliar density models. Satellite and ground observations can be combined to generate the accurate estimates of the species composition and foliar density required for natural VOC emission models.