Abstract
It is the most important and fundamental knowledge for climatology and hydrology to obtain the total incoming radition on the earth's surface in the world-wide view. But, in our country, we have no reliable tables or charts of this kind. Though we have several data in climatological atlases or handbooks, they are presented in the form of a distribution map. They are not desirable for the practical researchers. So the authors calculated values by using an empirical formula as an approach to the hydrological study, and the table of these values is shown for the convenience of other researchers.
In this calculation, Savinov's equation was used, because of restricted observational items in the climatological table. It is shown in the following form:
Q=Q0 (1-kn)
where Q0 denotes total incoming radiation in the cloudless case, k is coefficient and n represents amounts of cloud. Statististical values of the cloud amounts were taken from “Climatological Table of the Foreign Countries” published by Japan Meteorological Agency. Fundamental numerical constants were taken from Budyko's textbook (1956).
The authors examined reliability of the formula by comparing the calculated values to the observed ones. In Japan, observations of daily total incoming radiation are made by Robitzche actinograph, except for five stations. So, the results of these observations do not seem highly reliable, but they show rather good agreements except for summer months. The reason for the summer discrepancy will be dne both to the characteristics of the actinograph and to the formula. These comparisons are shown in Table 1, and the results of the calculations are listed in Table 2. All the figures are monthy mean valuse, the unit being cal/cm2/day.
