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Kondo, H., S. Murayama, Y. Sawa, K. Ishijima, H. Matsueda, A. Wada, H. Sugawara and S. Onogi, 2014: Vertical diffusion coefficient under stable conditions estimated from variation in the near-surface radon concentration. J. Meteor. Soc. Japan, 92, 95–106.
https://doi.org/10.2151/jmsj.2014-106

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Highlights:

• The time variations of estimated vertical diffusivity for radon (K_C) are shown in Fig.1, where assumed boundary layer height h = 25 m. As a reference, h for K_C = 0 at each time is also shown in Fig. 1. K_C and h are related in a quadratic equation for h.
• The relationship of φ(ς)∝ς^1/3 may be seen under a particularly strong stable condition because the term of friction velocity u* is included both in φ(ς) and in ς (self-correlation or spurious correlation). Figure 2 shows the relationship between φ(ς) and ς for the three groups of the data; ensemble averaged time series datasets grouping on time variation of radon concentration used in the present analysis (group 1), original 10-min averaged data (group 2), and randomly disordered dataset (group 3).
• Figure 2 demonstrates that the scatter of group 1 is rather small, that of group 2 is very large, and the scatter of φ(ς) in group 3 is correlated to ς^1/3 for a large value of ς with large scatter. The proposed formula of φ(ς) by Högström (1988) (φ(ς) = 1+6ς ) and another formula which suits the result of group 1 (φ(ς) = 1+2ς ) are added in Fig. 2 as a reference.