Browsing by Author "Pei, Xiangyu"

Atmospheric aerosol particles play an important role in atmospheric processes, and have a significant impact on global climate, air quality and human health. The climatic effects of secondary aerosol still represent one of the largest uncertainties limiting the understanding of climate change. The secondary aerosol originates from gas-to-particle conversion, which is also called New Particle Formation (NPF). NPF in the marine and coastal air has not been clearly studied. In many coastal areas new particle formation appears frequently, however, in remote marine environments, NPF events occur only occasionally. Moreover, some ship measurements have also been conducted to study nucleation on the ocean. The aims of this thesis are to obtain more information on neutral charged particles during the coastal NPF, to elucidate the different behaviors of negative particles and positive particles near the coastal line and on the ocean, and to speculate the mechanism of NPF. To achieve these goals, AIS and DMPS/SMPS are utilized to acquire the particles number size distribution during the ship cruise of CalNex 2010 campaign and at Mace Head, Ireland. The NPF days are classified based on the time series of the number size distribution. The growth rates and formation rates of particles, and other factors such as CS, solar radiation, SO2 concentration, ozone concentration, sulfuric and acid proxy and water level are also studied during the NPF event days to get the information and characteristics of the NPF near the coastal line. The backward trajectories are investigated to get to know the origin of the air mass when the NPF happened and the cluster analysis of backward trajectories are conducted to illustrate the relation between different origins of air mass and the frequencies of NPF events. The main outcomes of this thesis show that the dynamic processes of NPF and subsequent growth of particles in the marine and costal atmosphere are probably the same around the world. In general, sulfuric acid peak concentration was not correlated with the NPF in the marine and coastal atmosphere, other condensing vapors, such as organic vapors are needed to form the new particles and make them grow to large size. Low pre-existing particle concentrations and passage over land are necessary for NPF in the marine and coastal atmosphere. To improve the understanding of atmospheric NPF in coastal and marine environment, further field measurements and laboratory experiments should be conducted to monitor the gas-phase nucleating vapors and chemical compositions of neutral and ionic clusters and nano-particles simultaneously.