Concentration, Source And Activity Of Cloud Condensation Nuclei Over Qingdao, Yellow Sea, Bohai Sea And Northwest Pacific

Aerosol is very important to impact atmospheric cycle and climate system by direct and indirect effects.Cloud condensation nuclei (CCN)is one part of aerosol particles (condensation nuclei,CN)to activate and then grow as droplet, and play a key role in cloud and precipitation processes.The aerosol-cloud-precipitation interaction is the most important reason to cause large uncertain in assessing climate changes. With the quickening of the urbanization process in the mainland of China, anthropogenic aerosols could impact the regional climate directly or indirectly, furthermore, in a larger scale, further studies showed that Asian aerosol outflow could also impact the cimate over the affected area-the northern coast of China, the Yellow Sea and Bohai Sea and northwest Pacific.However, the observations on concentrations of CCN and CCN activities of aerosol particles in the areas were non-existed and the knowledge gap limits the understanding of the aerosol-cloud-precipitation relationship.Thus, we studied concentrations of CCN, different sources of CCN and variations of CCN activity measured over northwest Pacific，the Yellow Sea and Bohai Sea as well as in Qingdao.During the observation over northwest Pacific, concentrations of CCN were (0.70±0.38)x103 cm-3-(1.13±0.71)x 103 cm-3 (0.2%-0.4%SS),and the corresponding CCN activities of atmospheric particles were (0.29±0.11)-(0.46±0.20) (0.2%-0.4%SS).Ncen and AR varied highly with different regions.In the first-stage region (28°N～30°N,143°E～150°E), concentrations of CCN were relatively lower and they were mainly contributed by vertical transmission of terrigenous aerosols above the mixing layer and sea-salt aerosols caused by wave breaking.AR was relatively lower due to the particle size distribution dominanted by the Aitken mode.In the third-stage region (33°N～37N°,145°E-148°E), concentrations of CCN were relatively higher and they were mainly contributed by transmission of terrigenous aerosols above or under the mixing layer, sea-salt aerosols as well as the primary aerosols from biogenic emissions. AR was relatively higher due to the particle size distribution dominanted by the accumulation mode.During the observation over the Yellow Sea and Bohai Sea, concentrations of CCN were (2.52±1.04)x103 cm-3-(5.31±2.29)x103 cm-3(0.2%-0.4%SS),3.6-4.7 times of those over northwest Pacific.Concentrations of CCN were mainly effected by aerosols from Asian outlow, especially in Bohai Sea. Contribution of biogenic emissions could be neglected.AR were (0.27±0.11)-(0.53±0.17) (0.2%-0.4%SS).At 0.4% SS. AR were higher than those over northwest Pacific, indicating the AR enhancement by the single accumulation mode of aerosols over the coastal water. In additional,AR over the Yellow Sea were higher than over Bohai Sea as well as higher than over the coastal,showed that AR of terrigenous aerosols were improved after the longtime aging in the marine atmospheric environment.We studied concentrations of cloud condensation nuclei (CCN)and CCN activity measured at a suburb site of Qingdao in the north China during a non-heating period and a heating period.Concentrations of CCN during the non-heating period were 3.1±1.9,4.9±3.4,5.6±3.9,6.1±4.3 and 6.5±4.6 in unit of×103 cm-3 at SS of 0.2%. 0.4%,0.6%,0.8% and 1.0%, respectively. The corresponding CCN activities of atmospheric particles were O.28±0.17,0.43±0.24，0.48±0.26，0.52±0.27 and 0.54±0.28.respectively.Concentrations of CCN during the heating period were 3.1±1.3.6.4±2.3,8.5±2.9,9.6±3.5 and 10±3.9 in unit of×103 cm-3 at SS of 0.2%. 0.4%,0.6%,0.8% and 1.0%, respectively. The corresponding CCN activities were 0.11±0.06，0.24±0.11,0.31±0.14,0.35±0.15 and 0.37±0.15. respectively.At SS>0.4%, concentrations of CCN were significantly larger during the heating period than during the non-heating period with 95% confidence because of larger particle number concentrations associated.However, CCN activities were significantly lower during the heating period than during the non-heating period at each SS.The lower CCN activities during the heating period were analyzed in terms of origins, median mobility diameter and possible chemical composition of atmospheric particles. However, when new particle formation events during the heating and the on-heating periods were considered alone, CCN activities of grown new particles at the same size range sometimes appeared to be constant regardless of the heating or non-heating periods.