Surface CCN measurements at mace head, on the west coast of Ireland

Abstract

The influence (though indirect) of the cloud condensation nuclei (CCN) population on the radiative properties of cloud, and hence on global climate is a subject of increasing interest and attention since the work of Twomey, who calculated an increase in cloud albedo due to increased CCN number concentration. The currently more accepted climatic role of CCN has resulted in a drive for more worldwide measurements of CCN through programs, such as the World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) aerosol program. This chapter presents surface measurements of cloud condensation nuclei (CCN) number concentration for unmodified marine air and for polluted air at Mace Head, for the years 1994 and 1995. The CCN number concentration is found to be approximately log-normal for marine and polluted air at the site. Values of geometric mean, median, and arithmetic mean of CCN number concentration for marine air are in the range 130-135, 140-150, and 137-157, for the two years of data.