降雪粒子の密度と粒径分布は，気象学的に重要であるが，連続測定は難しい.本研究では，粒子密度や粒径分布などの物理特性を連続して自動測定することを目標として，まず高速力メラを用いて落下中の降雪粒子を側方から撮影する.次に連続画像間での粒子の形や移動量などから粒子追跡を行う.同時に，電子天秤で降雪重量の増分を計測し，粒子数，粒径，落下速度から粒子密度を推定する.冬季の観測実験の結果，降雪粒子の粒径分布および密度の時間変化が得られた.%The density and size distribution of falling snow particles are important in meteorology, but it is difficult to measure them continuously. In this study, we propose the system to measure them automatically by image processing. First, Images of falling snow particles are taken from the side using a high speed camera. Next, each particle in the image is detected and then tracked continuously using the shape, size and moving distance between the correspondence particles. At' the same time, the increment of the snow weight is measured using three electronic balances, and then the snow density is estimated by calculating the number, diameter and fall velocity of particles. By the analysis of snowfall observations in last winter, we obtained the time series of size distribution and density of the snow particles.
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