Abstract
Aerosol particles acting as cloud condensation nuclei (CCN) determine initial cloud droplet concentrations and subsequent evolutions of microphysical structures of clouds and precipitation, and affect a short-range precipitation forecast and climate change projection. The Global Atmosphere Watch Scientific Advisory Group recommends the CCN monitoring as a part of determination of the spatio-temporal distribution of aerosol properties related to climate forcing and air quality on multi decadal time scales and on regional, hemispheric and global spatial scales. We have been monitoring CCN concentrations along with aerosol concentrations, aerosol size distributions, and ice nuclei (IN) concentrations on the campus of Meteorological Research Institute in Tsukuba city (36.06°N,140.13°E), Ibaraki, Japan since March 2012. In this report, the maintenance information for long-term measurements with continuous-flow stream-wise thermal gradient chamber type CCN counter, especially calibration methods of supersaturations in the CCN counter and their error factors, are described. Also, the results of the long-term monitoring of CCN concentrations and the research activity on cloud droplet formation processes at MRI are briefly introduced.
