Recently, concerning to the air pollution problems, both the structure of turbulence in the atmospheric surface layer and meteorological parameters with regard to atmospheric diffusion in light-wind have been interested.
In order to investigate the character of turbulence in light-wind, the R. M. S. of horizontal wind fluctuation (that is, longitudinal and lateral components) and directional wind fluctuation have been compared with mean wind speed and sampling duration, respectively.
Main results became clear in the present observation are summarized as follows.
(1) It seems that σA=σ_θS does not hold as U decreases.
(2) σ_θS decreases with increasing of U and σ_θS in daytime is larger than in night.
(3) The ratio σ_υ/σ_u is 0.97 in daytime, 1.17 in night.(Each value is mean value of 18 data.)
(4) Dependency of σ_u and σ_υ on mean wind speed U changes at the vicinity of U=1.5m/s. For wind speed larger than this critical level, these R. M. S. values are proportional to U^3/2, but smaller than this, there are no regular relations.
(5) σ_θS, σ_u and σ_υ increase with increasing the length of sampling duration, but aproached the saturation in about 20 minutes.

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Atmospheric concentration of nitrogen oxides was analyzed. The averaged amounts showed that there exist the annual variation of factor 2 and the diurnal variation of factor 1.5 for nitrogen dioxide.
A trial was made to divide the concentration into twe components from the standpoint whether it depends on the human population or not, which are named A and N component, respectively.
N component was shown to play the dominant role in the annual variation which has a maximum in winter. And the level of nitrogen dioxide in the daytime was shown to be mainly attributed to the A component. The daily amounts of A component is about 2.5 times of that of N component as an average.
Modelling of the variation of nitric oxide was also performed, and compared with the data which shows fair agreement.

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