Primary Study on the Real-Scale Cloud Experiments in a Long Vertical Shaft

本项目原计划在1993至1994财政年度期间在北海道神岛川三井煤矿公司的南井井进行。然而，1993年9月，竖井突然关闭，迫使我们寻找另一个适合实验的竖井。经过几次询问和谈判，1994年11月与岩手县的Kamaishi矿业公司就使用他们的一个矿井达成了协议，但由于设施的修理和对环境条件的初步观察，直到1995年3月才开始使用。经过这些努力，1995年4月进行了第一次云实验，10月进行了第二次云实验，并取得了一些结果，实现了本项目的一些最初目的。在这两个实验中，都观察到云是在大约十到几十米的高度形成的。二氧化硫（SO_2）以1l/min的低排放速率在竖井底部排放，并与硫酸盐气溶胶浓度一起测量了其在云中和地下的浓度。测定了云水中硫含量。结果发现，硫的总量至少在云层底部的下方和上方是守恒的，而且几乎所有的SO_2在上升气流中被云水吸收。在第2次试验中，用装在提升机上的SO_2计获得了SO_2浓度的垂直分布。浓度分布用双指数函数表示，在云底以下和云底以上的高度有两个不同的衰减常数。云内衰变的半衰期为80 s，表明降雨过程迅速。在竖井顶部也观察到了云滴的大小分布。大小分布基本呈单峰分布，在9株左右出现一个高峰，在30株左右出现第二个高峰。这些大液滴也被水蓝膜法检测到。这些水滴的数量浓度不高，但它们对云水含量有显著的贡献。少

This project was originally scheduled for the period from 1993 to 1994 fiscal years to be carried out in the Nambu Shaft of Mitsui Coal Mining Co.in Kamisunagawa, Hokkaido. However the sudden closure of the shaft in September, 1993, forced us to search for another one suitable for the experiment. After several inquiries and negotiations, an agreement was reached in November, 1994, with Kamaishi Mining Co.in Iwate Prefecture on the use of one of their shafts, but it did not become usable until March, 1995, because of the repairment of facilities and the preliminary observation of enrivonmental conditions. After all these efforts, the first cloud experiment was done in April, 1995, and the second in October, and several results were obtained which fulfillled some of the original purposes of this project.In both of the experiments, it was observed that cloud was formed at altitudes of about ten to several tens of meters. Sulfur dioxide (SO_2) was emitted at the base of the shaft with a fl … More ow rate of about 1l/min, and its concentration was measured below and in the cloud together with the sulfate aerosol concentration. The sulfur content in the cloud water was also measured. As a result, it was found that the total amount of sulfur was conserved at least immediately below and above the cloud bottom, and also that almost all SO_2 was absorbed into the cloud water as it flowed in an updraft. In the second experiment, the vertical distribution of SO_2 concentration was obtained by an SO_2 meter loaded on the elevator. The concentation distribution was expressed by a double exponential funciton with two different decay constants for the altitudes below and above the cloud bottm. The half-life for the in-cloud decay was 80 s showing the rapidity of the rainout process. Cloud droplets size distribution was also observed at the top of the shaft. The size distribution was mostly monomodal with a peak around 9 mum, but a second peak appeared intermittently around 30 mum. Those large droplets were detected by the Water Blue Film method as well. The number concentration of those droplets was not high, but they were found to have significant contribution to the cloud water content. Less