Global electric circuits could be the key link between space weather and lower atmosphere climate. It has been suggested that the ultrafine erosol layer in the middle to upper stratosphere could greatly contribute to local column resistance and return current density. In previous work by Tinsley, Zhou, and Plemmons (Atmos. Res., 2006, 79 (3–4), 266–295), the artificial ultrafine layer was addressed and caused a significant symmetric effect on column resistance at high latitudes. In this work, we use an updated erosol coupled chemistry-climate model to establish a new global electric circuit model. The results show that the ultrafine aerosol layer exits the middle stratosphere, but due to the Brewer-Dobson circulation, there are significant seasonal variations in the ion loss due to variations in the ultrafine aerosol layer. In the winter hemisphere in the high latitude region, the column resistance will consequently be higher than that in the summer hemisphere. With an ultrafine aerosol layer in the decreasing phase of solar activity, the column resistance would be more sensitive to fluctuations in the low-energy electron precipitation (LEE) and middle-energy electron precipitation (MEE) particle fluxes.
Total suspended particles (TSP) samples from 7 stations of various functional areas in the center region of Shanghai were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) during 2008 winter, and the source of the PAHs was also distinguished. The results show that TSP concentrations were higher than the value World Health Organization recommended(Value of Average daily<0.12mg/m 3 ), there was difference in total PAH concentration among 7 samples between 0.10 mg/m 3 and 0.24mg/m 3 . The contents of PAHs gradually decreased from the outer to the inner ring. There is a peak in campus because of its surrounding. The PAHs may come from the oil and incomplete burning of coal. Based on the measured concentration of the PAHs, BaP equivalent (BaP eq ) was derived based on Toxicity Equivalent Factors (TEFs) of the PAHs. The total BaP eq values of different stations were higher than the value World Health Organization recommended(1ng/m 3 ), from 2.796 ng/m 3 to 7.491ng/m 3 .The contributions of PAHs with five and six rings contributed 80% of the total toxicity, while they accounted for only 30% of the total concentration. The PAHs of each function area mainly come from local pollution emissions.
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