Dr. Jianmin Ma Atmospheric Environment Service (AQRI) 4905 Dufferin Street, Downsview, Ontario, Canada. M3H 5T4 Tel: (416) 739-4857, Fax:(416) 739-4288 e mail: jianmin.ma@ec.gc.ca
Computation of Surface Concentration Fluxes and Dry Deposition Velocities of O3, CO2 and SO2 from A Variational Method Using Measured Variance and Single Level Concentration Data
JIANMIN MA1 and S. M. DAGGUPATY2 1. Skiman Modlling, 4905 Dufferin Street, Downsview, Ontario M3H 5T4, Canada 2. ARQI, Atmospheric Environment Service, Downsview, Ontario M3H 5T4, Canada
Abstract - Surface fluxes and dry deposition velocities of O3, CO2 and SO2 were estimated from a variational method by using measured single level concentrations and concentration variances (standard deviations) of these trace gases. The measurements were taken over a deciduous forest when it was fully leafed during the summer of 1988 and when it was leafless during the winter of 1990. A flux-variance relation and a flux-gradient relation were employed as constraints in a cost function which is minimized to find the optimal estimate of concentration fluxes of interested trace gases. Concentration fluxes of O3, CO2 and SO2 from the variational method were compared with the fluxes estimated from the flux-variance relation and measurements. Results show that the variational method proposed in this study improved significantly the computation of the concentration fluxes by the use of the flux-variance relation. A comparison of estimated and measured dry deposition velocity for O3 and SO2 was also carried out by use of estimated and measured concentration fluxes. The flux-variance relation overestimated apparently the deposition velocities of O3 and SO2; whilst the variational method reduced considerably the overestimation of the dry deposition velocities and yielded comparable deposition velocities with the measurements.
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