Study on New Particle Formation, Particle Growth, and Cloud Formation at the summit of Mt. Fuji, Japan

摘要

New particle formation (NPF) is important process by increasing the number of cloud condensation nuclei (CCN) and changing properties of cloud. However, there are a few reports from high-altitude in East Asia. As the summit of Mt. Fuji, Japan is usually positioned in the free troposphere, we can measure the size distribution of aerosol particles in the free troposphere. Our purpose is to clarify the mechanism of NPF, particle growing, and cloud formation. Observations were performed at the summit (3776m ASL, 35.36 N, 138.73 E) in July and August 2006 to 2014. Size distributions from about 10 nm to 5000 nm in diameter were measured with a scanning mobility particle sizer (SMPS, TSI 3936N25, 3936L22, or 3034) and an optical particle counter (OPC, RION KR12 or KC01E). CCN concentration was measured with CCN counter (DMT CCN-100). Radon concentration was calculated from concentration of radioactive aerosols collected on a filter. Concentration of small ions was measured with a Gerdien type meter. For aerosols the sample air was dried to lower than 20% relative humidity with a diffusion dryer. According to the backward trajectories, air masses were classified into the five air mass origins, Continental, Land and Sea, East China Sea, Japan, and Maritime. Condensation sink, coagulation sink, formation rate, growth rate, and the effective hygroscopicity parameter were calculated.