Analyses and comparisons of variations of Be-7, Pb-210, and Be-7/Pb-210 with ozone observations at two Global Atmosphere Watch stations from high mountains

作者：Lee H N^*; Tositti L; Zheng X; Bonasoni P

来源：Journal of Geophysical Research, 2007, 112(D5): D05303.

DOI：10.1029/2006JD007421

Simultaneous measurements of Be-7 and Pb-210 and the analyses of activity ratio, i.e., Be-7/Pb-210, offer another useful analytical tool for improving our understanding of ozone variability occurring at high altitude because they can provide diagnostic indicators of horizontal and vertical transport processes. Generally, the increase (decrease) of Be-7 with decrease (increase) of Pb-210 in association with high (low) values of Be-7/Pb-210 indicates the mechanisms associated with vertical (for being favorable to the horizontal) transport processes. For the purpose of demonstrating these mechanisms for ozone transport, we have presented the distinct transport processes of ozone and background conditions for two Global Atmosphere Watch ( GAW) stations: Mount Cimone station (44.18 degrees N, 10.7 degrees E, 2165 m asl) and Mount Waliguan station (36.29 degrees N, 100.90 degrees E, 3816 m asl), located high in the mountains of Italy and China, respectively. We have performed the frequency distribution analyses and various comparisons of variations of Be-7 with Pb-210 and variations of Be-7, Pb-210, and Be-7/Pb-210 with surface ozone. The maximum ozone levels occur in the summer, and minimum levels occur in the winter at these two high mountain stations. Our analyses suggest that the processes of the stratospheric intrusions/upper tropospheric transport combined with the long-range transport from polluted areas over eastern central China are the mechanisms that cause the ozone summer peak at the Mount Waliguan station. The ozone summer peak at the Mount Cimone station is mainly the result of photochemical production in the lower atmosphere associated with the transport of polluted air masses on regional and continental scales. Frequency distributions of Be-7, Pb-210, Be-7/Pb-210, and surface ozone can be well represented by the lognormal distributions. Strikingly, we have found that the similarities of bimodal distributions for Be-7/Pb-210 at these two stations are clearly exhibited except for the magnitude, although the lognormal distributions of Be-7 and Pb-210, with the noteworthy difference in altitude of these two stations, are significantly different. The measurements of Be-7 and Pb-210 combined with the analyses using Be-7/Pb-210 activity ratio can enhance our understanding of the transport processes in the atmosphere.

• 出版日期2007-3-8
• 单位中国气象科学研究院