Cosmogenic 7Be: Atmospheric Concentration and Deposition in Japan

Interactions between cosmic rays and atmospheric components produce various nuclear fragments. Cosmogenic 7Be distributes uniformly in the atmosphere which covers all over the earth. Thus, the vertical and horizontal transport of 7Be in the stratosphere as well as troposphere will work as an effective tracer with half life of 53.3 days. Many studies have been conducted on 7Be atmospheric concentration and deposition onto the ground. Generally, the atmospheric 7Be concentration and the 7Be deposition show seasonal and yearly variations which are controlled by solar activity, cosmic ray intensity, atmospheric circulation and other mechanisms such as “washout” and “rainout”. This paper presents atmospheric 7Be concentration and 7Be deposition data obtained by the authors as well as other investigators. The variations of atmospheric 7Be concentration and 7Be deposition and their influential factors are also reviewed.