On the variation of the amount of giant sea-salt particles near the ground

The number concentrations of giant sea-salt particles for each salt-mass near the ground were observed in Kagoshima, from September 4, 1962 through October 1, 1963, The particle number concentration (PNC) often increased during the approach and the passage of cyclones or fronts, and of typhoons. The low number concentrations of sea-salt particles occurred under the meteorological conditions of the comparatively long period of rainfall, such as Bai-u, and the partly cloudy condition due to anticyclones. It is found that there is a seasonal variation in the monthly mean PNV, which has maxima in winter and summer and minima from late spring to early summer and autumn. The amount of the monthly mean PNC may be related to both the monthly mean wind speed and precipitation. The salt-mass distributions of sea-salt particles in several characteristic meteorological conditions are presented. Aspects of the increase of PNC caused by the approach and the passage of cyclones or fronts depend largely on the increase or the decrease of the distance from coast, as well as on the amount of precipitation, in comparison with those in the previous 1 or 2 days. The impaction-sedimentation ratio, tau , is estimated from the observations of PNCs in different wind directions under the anticyclonic meteorological conditions. The value of tau estimated is 2-5 for 2, 3, 4m/sec, and 3-20 for 5, 6, 7 m/sec in wind speed, respectively.