Monitoring and Visualization of Aerosol Distribution and Flow Pattern from Main Streets to Residential Quarter

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There were two purposes in this research ; l) development of a new monitoring system capable of aerosol detection in the atmosphere which was exhausted from motorcars and diffused by their running, 2) visualization of the aerosol distribution, diffusion and flow pattern from main streets to residential quarter using the observed data with the system developed.Laser remote sensing system with a Nd : YAG Iaser was newly developed for these purposes. The system was capable of aerosol monitoring with range resolution of 10-100m, time resolution of within several minutes. The system was scanned automatically in the horizontal direction with a stepping motor and enabled a global real time monitoring over a radius of 7km.Results of horizontal observation showed a high density aerosol area surrounded by several main streets such as Route 18 and Route 406, and others. This suggested a flow of the high density aerosol caused by motorcars from the main streets to the residential quarter. We had concern about the effect on public health. Results of vertical observation showed a long time residence of high density aerosol near the suface at night time. It seemed that aerosol exhausted heavily from motorcars during daytime, whose density was low at daytime by the daytime convection, was condensed at nighttime with decreasing a hight of the atmospheric mixed layr.A program introduced a new analysis method given by Fernald, which made a possible to seperate aerosols from air molecules, was applied to the observed data. It was important to evaluate the boundary condition depending on a value of signal to noise ratio in the observation. The value of>10 was required to get reliable results. The vertical distribution of high density aerosol was clearly shown and visualized by the program.