Citation:

Goodwitch, J. VERTICAL OZONE FLUXES AND RELATED DEPOSITION PARAMETERS OVER AGRICULTURAL AND FORESTED. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/154 (NTIS PB91109926).

Description:

The spatial variability and temporal behavior of the vertical flux of ozone has been investigated from turbulence measurements collected on aircraft flight legs in the daytime period during two consecutive summer experimental field studies. he data were obtained during horizontal flight legs conducted over agricultural crops and forested land in southeastern Pennsylvania, central Ohio, and western Tennessee/Kentucky. esults from individual experimental cases and statistics derived from all cases in each region are presented. zone flux generally exhibited a significant height dependency; strongest negative (downward) fluxes in the lowest level flight legs were primarily attributed to the uptake of ozone by the surface and vegetative cover while values were near-zero in the middle of the convective boundary layer in the afternoon period. s ozone flux was proportional to concentration, slightly higher fluxes were found in low level downwind urban plume segments where ozone concentrations were 10-20 ppb higher than in the surrounding area. erived deposition velocity showed no such bias as a function of position across the urban plum. zone flux differences were not apparent between the more heavily forested sections and the primarily agricultural cropland areas in these regions. uring the afternoon period when no clear temporal trend was evident, means from values obtained below O.l5Zi (Zi being the convective boundary layer height) were -0.421 and -0.431 ppb m/s for ozone flux and 0.81 and 0.82 cm/s for the deposition velocity in the southeastern Pennsylvania and central Ohio areas, respectively. alues from Tennessee/Kentucky flights were much smaller because of reduced uptake under the hot, dry conditions.

Record Details:

Document IDs: