Departmental Bulletin Paper Detection of invisible SPM distribution in the sky

Toru YAGI  ,  Junko KAMBE  ,  Tomoo AOYAMA

Suspended Particulate Matter (SPM) is dusts in the atmosphere, which exists from ancient times. Nowadays, they have two origins that are natural and artificial. The diameter is distributed between 1 ~ 10 μm. Natural SPM is almost soil particles, and includes bacteria and virus on the surfaces. Artificial SPM is industry by-products; that is, complex matters over one hundred kinds of compounds. Even if SPM is under the gravity, the falling speed is negligible, and it moves as well as the gas. As property of small particles, it attracts many substances. If SPM moves through polluted air, it transports contamination matters towards leeward. The phenomenon is found beyond countries. An example is the yellow sand arising from Taklamakan desert flows until Greenland. SPM is a meteorological word. We hear it as “PM2.5” in various media. Very concentrated SPM makes the sky be cloudy. The phenomenon is not found yet in Japan. Existence of dilute SPM is detected as hazy sky, which degree is small. Therefore; we detect the haze by using digital cameras. We have observed the SPM at Norikura observatory from 2011 until 2016. This is a report of the digital measurements and discussions of the image processing. Where, conception of physical color, meaning of color-ratio, contouring image approach as extraction of character of targets, two dimensional Fourier Transformation are discussed.\n Figures are drawn by using full color. The true images will be got from Web-pages.

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