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FLUXES OF GASES AND PARTICLES ABOVE A DECIDUOUS FOREST IN WINTERTIME
Citation:
Wesely, M., D. Cook, AND R. Hart. FLUXES OF GASES AND PARTICLES ABOVE A DECIDUOUS FOREST IN WINTERTIME. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-83/361.
Description:
Eddy-correlation measurements of the vertical fluxes of ozone, carbon dioxide, fine particles with diameter near 0.1 micrometers, and particulate sulfur, as well as of momentum, heat and water vapor, have been taken above a tall leafless deciduous forest in wintertime. During the experimental period of one week, ozone deposition velocities vary from about 0.1 cm s(-1) at night to more than 0.4 cm s(-1) during the daytime, with the largest variations associated primarily with changes in solar irradiation. Carbon dioxide fluxes are directed upward, due to respiration in the leaf litter and soil beneath the canopy, and exhibit a strong dependence on air temperature. The fluxes are approximately zero at air temperatures less than 5 C and approach 0.8 mg m(-2) s(-1) when temperatures exceed 15 C during the daytime. Fine-particle deposition rates are large at times, with deposition velocities near 0.8 cm s(-1) when turbulence levels are high, but fluxes directed upward are measured above the canopy when the surface beneath is covered with snow. Deposition velocities for particulate sulfur are highly variable and average to a value small in magnitude as compared to similar measurements taken previously over a pine forest in summer. (Copyright (c) 1983 by D. Reidel Publishing Company.)