降下ばいじん量と降水量の間の関係について(IV)

Abstract

Utilizing the data of the dust-fall and rain-water measurements through a deposit-gauge net-work at Kasugai city (Aichi pref.) for the space of 1985 to 1987,at Kushiro city (Hokkaido) and Atsumi town (Aichi pref.) for 1986 to 1987,we have made sure of the relations between dust-fall and rain-water quantities to which we had referred in previous reports, and then, in the same way as that in the previous ones, we have calculated the collection efficiency of a rain-drop for a dust-particle and further, the amount of air-suspending dust, a portion of which might be scavenged by rain. By taking into cosideration the results so obtained together with those we had indicated in the previous reports, we have come to the conclusion that, throughout the districts we had hitherto surveyed, (1) the collection efficienency be generally of the order of (10)^<-2> for rain-drops of 0.5～1mm diameter against dust-particles of 4～10μm diameter under rain-fall intensities of 0.1～1mm/h, and (2) the amount of suspending dust be of the range of 3～5t/km^2・mo. Additionally, we have contrived a more direct and precise treatment to calculate these quantities and have applied it to some of the 1987 data at Kasugai city in the present report, the result being such that (1) the magnitude of the collection efficiency gets 2～3 times greater, with little difference in order and (2) the amount of suspending dust remains nearly unchanged.