Abstract:Based on the cloud condensation nuclei (CCN) concentration and aerosol size distribution measured at the Wuqing Meteorological Service of Tianjin from November to December of 2009, the variation characteristics of CCN concentrations and activation rates at different degrees of supersaturation (01% to 10%) are analyzed. The results show that the CCN concentration varies in the range of 4000 to 32000 cm-3 in the supersaturation of 1% and is affected by the wind speed significantly at Wuqing in winter. Under the wind speed of 15 to 33 m/s, the CCN concentration is very high, can reach 16000 cm-3 at 1% supersaturation, but is just one forth of that under the wind speed of 35 to 55 m/s. The CCN concentration varies greatly in the range of 01% to 04% supersaturation. The increase of CCN concentration for every 01% supersaturation in the range of 01 to 04% is about 5 times of those in the range of 04% to 10% supersaturation. The activation rate is affected significantly by the wind speed at the low supersaturation (01%, 02%), and the value under the wind speed smaller than 15 m·s-1is about three times of that under the wind speed larger than 55 m/s, but at the supersaturation of 1%, the activation rate difference with wind speed is little. The diurnal variation of CCN concentration shows two peaks at 08:00 and 18:00, as there are two valleys in the diurnal variation of the activation rate, which suggests the effects from the local emissions. The power law fitting for the relationship of CCN concentration and supersaturation under different wind speeds shows that the supersaturation spectrum of CCN at Wuqing belongs to the continental style.