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Lee et al. 2004
Lee, H.N., Wan, G., Zheng, X., Sanderson, C.G., Josse, B., Wang, S., Yang, W., Tang, J. and Wang, C. (2004). Measurements of 210Pb and 7Be in China and their analysis accompanied with global model calculations of 210Pb. Journal of Geophysical Research 109: doi: 10.1029/2004JD005061. issn: 0148-0227.

Previous global models generally simulated high concentrations of 210Pb in the surface air over China. Measured data of 210Pb are needed in order to examine the accuracy and performance of the models. We collected the first-ever set of surface air radionuclide measurements of 210Pb and 7Be at Guiyang (26.57¿N, 106.72¿E, 1080 m above sea level) on the east of the Himalayas in Guizhou Province and at Mt. Waliguan (36.29¿N, 100.90¿E, 3816 m above sea level), a Global Atmosphere Watch station for the World Meteorological Organization, on the Qinghai-Tibetan plateau extending from the Himalayas in Qinghai Province, China. These measurements were carefully analyzed for data assurance and quality control and were used for validating models. The patterns for the variations in both measured 210Pb and 7Be at the Guiyang site have been shown to be consistent. In this case the increase of 7Be concentration was the result of the weak subsidence of air developed at the periphery of the high-pressure system. Because of the weak subsidence the boundary layer turbulence could mix the upward transport of 210Pb, thus increasing 210Pb concentration. The ratio of 7Be/210Pb indicated a seasonal variability with rough monthly oscillation. The ratio peaks were in spring and summer when the convective activities were significant. The 210Pb levels measured at Mt. Waliguan, located at the peak of the mountain, could be attributed to the long-range transport of 222Rn that decays to 210Pb, whereas the 7Be concentration varied directly with the local airflow passing over the site. We found that it was not appropriate to use the ratio of 7Be/210Pb for analysis of vertical transport exchange processes at the high-altitude Mt. Waliguan site because of the long-range transport of 210Pb that occurred at the site. For the purpose of model validation we have simulated the global transport of 210Pb for the year 2002 by using a comprehensive multiscale three-dimensional global chemical transport model developed by M¿t¿o France. It was found by comparing model results with measurements that the model generally performed poorly for the calculations of 210Pb concentrations in China. The underestimates of model results could be the result of the unidentified high radon sources over China. However, the model was able to reproduce the variations of the 210Pb concentrations.

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Abstract

Keywords
Atmospheric Composition and Structure, Constituent sources and sinks, Atmospheric Composition and Structure, Troposphere—constituent transport and chemistry, Exploration Geophysics, Radioactivity methods, radionuclide measurements, 210Pb and 7Be, global transport, global network, global model validation
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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