Radiative Flux Components Research Articles

Measurements on the radiation balance in the Tottori Sand Dune were made, especially on the total short-wave radiation, the net radiation and the albedo as a function of the soil moisture ratio. The results were as follows:1. Continuous observations of the radiation flux components showed that the ratio of the net radiation to the total short-wave radiation, S/(Q+q), varied from 0.38 to 0.65 and 0.48 in average, where Q is the direct short-wave radiation and q is the diffused short-wave radiation. The ratio was generally larger in the cloudy day than in the clear day. In the non-dimensional equation of the radiation balance, S/(Q+q)=(1-a)-F/(Q+q), here a denotes the albedo and F is the effective long-wave radiation, the variations in the term of the left-hand side were affected by those of right-hand side with the weights of the ratio 2:3.2. According to the results observed in the clear day of August, 1970, both the total short-wave radiation and the net radiation showed the maximum value, 1.22 and 0.68ly/min. respectively, at noon and the ratio of the latter to the former was 55.7%. Also, it was showed that the upward total radiation containing the short-wave radiation at noon was about 0.55ly/min and it was equivalent to 45% of the downward total short-wave radiation3. The obvious diurnal variations in the albedo were found in the clear day of July through October, as seen from Fig. 5. The value in average was in the range of 26.5-28% and the value of the albedo was higher in the fall than in the Summer. Concerning the relation between the albedo and the moisture ratio, the albedo increased with decreasing of moisture, especially below 3% of soil moisture (Fig. 6 and 7).

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