10 Characteristics of Aerosols, CCN and IN Abilities from Ground-Based Observations at Tsukuba, Japan

Monday, 9 July 2018
Regency A/B/C (Hyatt Regency Vancouver)
Narihiro Orikasa, MRI, Tsukuba, Ibaraki, Japan; and A. Saito, K. Yamashita, T. Tajiri, Y. Zaizen, T. H. Kuo, and M. Murakami

In order to characterize the abilities of atmospheric aerosols to act as cloud condensation nuclei (CCN) and ice nuclei (IN), we have conducted the ground-based monitoring observations since March 2012 at Tsukuba, Japan (36.06°N, 140.13°E), by using a CCN counter (CCNC), continuous-flow-diffusion-chamber type IN counter (INC), scanning mobility particle sizer (SMPS), optical particle counter (OPC), and aerodynamic particle spectrometer (APS).

The average number concentration of CCN was about 2,300 cm-3 at a water supersaturation (SSw) of 0.5%. The CCN concentration showed the seasonal trends of higher in winter and lower in summer. The number concentration of IN was about 5 L-1 on average at a temperature of -25 C over the range of SSw from 0 to 5%. The IN concentration had a large variability with some trends of higher in late spring or early summer.

The median values of hygroscopicity of aerosols were 0.1 (SSw=1.0%) to 0.35 (SSw=0.1%). Their median of ice nucleation active site (INAS) density was on the order of 107 m-2 from -15 to -35 C with weak dependency of temperature. The results in this study will be compared with previous studies.

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