Effects of dry deposition on the concentration-distributions of atmospheric pollutants within land- and sea-breeze circulations

In a land- and sea-breeze situation, effects of dry deposition on the dynamics of the concentrations of chemically reacting air pollutants are investigated using a transport/transformation/removal model with diurnally varying deposition velocities modeled in terms of the aerodynamic, surface, and residual resistances. The results show that the diurnally varying flows and eddy diffusivities, which are characteristic of the landand sea-breeze system, transfer the effects of dry deposition on the concentrations quickly to the upper layer over the land and sea surfaces. The dry deposition effect on one species can be transmitted to others through the network of chemical reactions, e.g. inclusion of dry deposition into the simulation resulted in the increase of hydrocarbon concentrations. It is also predicted that the dry deposition processes could remove a considerable part of emitted NOx, and SO2 from the local circulations, e.g. for 2 days about 40% of the emitted NOx was removed by the dry deposition of NO, NO2, HNO3 and PAN and in the case of SO2, 25 % by that of SO2 and SO42−.