Concentration of small ions measured at the center of Tokyo, at the summit of Mt. Fuji, and over the Pacific Ocean

/Introduction/ It has been proposed that climate could be affected by changes in cloudiness caused by variations in the intensity of galactic cosmic rays in the atmosphere. The cause of it is considered as a new particle formation with ion induced nucleation. The ion induced nucleation is occurred under the low concentration of particles and high concentration of ions, but there are a few reports. Then we have observed small ions, aerosol size distributions, radon concentrations, and intensity of cosmic rays at the summit of Mt. Fuji simultaneously. We also observed the similar elements at the center of Tokyo and over the Pacific Ocean. /Methods/ Observations were performed in summer in 2010 and 2011 at the summit (3776m ASL) and in summer in 2011 at Tarobo (1290m ASL), at the base of the Mt. Fuji and from autumn in 2010 to summer 2011 at the center of Tokyo, and from 1st December 2011 to 6th March 2012 on the R/V Hakuho Maru over the Pacific Ocean. Small ions were measured with the Gerdien type meter (COM-3400). The critical mobility was set 0.7 cm2/V/s and we measured positive and negative ions alternately. Size distributions from 4.4 to 5000 nm in diameter were measured with a scanning mobility particle sizer (SMPS, TSI 3936N25 or 3936L22) and an optical particle counter (OPC, RION KR12 or KC01D). Radon concentration was calculated from concentration of radioactive aerosols collected on a filter. Small ions are generated with ionization of air by cosmic rays or radiation from radioactive substances. Small ions are lost by various mechanisms such as ion-ion recombination and ion-aerosol attachment. /Results and Discussion/ Hourly averaged concentration often showed the diurnal pattern of high in the early morning and low in the evening at Kagurazaka, Tarobo, and the summit in 2010. However, the different pattern of low in the early morning and high in the evening was often observed at the summit in 2011. This pattern had observed by some investigaters. New particle formation with ion-induced nucleation was observed once at night. There is a possibility of descending of stratosphere air mass and low concentration of particles during the period. Conductivity measured on mid-March in Tokyo showed high values. Its variation was well accorded with that of dose measured in the Tokyo Metropolitan Institute of Public Health 4km far from the observation site. Then we regarded this event was the transport of radioactive substances from the Fukushima Daiichi Nuclear Power Station. We estimated the air mass size of radioactive substances from decreasing rate of conductivity. After March 23, the decreasing rate of conductivity became low. We judged the source of ionization was the deposition of radioactive substances and estimated the removal rate of deposition around the site. /Acknowledgments/ This study was partly supported by the Grants-in-Aid for Scientific Research, Category C (Grant No. 22510019), from JSPS. This work was partly performed during the period in which the NPO "Valid Utilization of Mt. Fuji Weather Station" maintained the facilities.