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

这项研究有两个目的； l) 开发一种新的监测系统，能够检测汽车排出的大气中的气溶胶并通过其行驶扩散，2) 使用开发的系统观测到的数据，对从主要街道到住宅区的气溶胶分布、扩散和流动模式进行可视化。为此，新开发了带有 Nd: YAG Iaser 的激光遥感系统。该系统能够进行气溶胶监测，距离分辨率为10-100m，时间分辨率在几分钟内。系统通过步进电机进行水平方向自动扫描，实现半径7公里范围内的全球实时监测。水平观测结果显示，18号公路、406号公路等多条主要街道周围存在高密度气溶胶区域。这表明汽车产生的高密度气溶胶从主要街道流向住宅区。我们担心这对公共健康的影响。垂直观测结果显示，夜间高密度气溶胶在地表附近长时间滞留。看来，白天从汽车中排出的气溶胶在白天的对流作用下密度较低，在夜间随着大气混合层高度的降低而凝结。一个程序引入了Fernald给出的一种新的分析方法，使气溶胶与空气分子分离成为可能，并将其应用于观测数据。根据观测中的信噪比值来评估边界条件很重要。需要>10 的值才能获得可靠的结果。该程序清楚地显示和可视化了高密度气溶胶的垂直分布。

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.