Abstract
On the basis of solar radiation data of the Eppley 180°-pyranometer and the duration of sunshine of the Jordan: sunshine recorder on six sta-AiOns through a sevenvear period, we eXarnined the coefficients as -well as the correlation Coefficient of empirical regression lines of the form Q/Q0=a+b n/N (where Q and Q0 are the monthly mean vojues of daily total amount of solar energy falling on a horizontal surface, each with and without the atmosphere respectively, and n/N denotes the ratio of measured duration of sunshine to maxime 'possible values of respective month). Calculations were done from four points of view, that is monthly trend of each station, annual mean of each station, monthly trend of all the stations put together, and the total mean of the same.
According to the results of calcutation, the correlation coefficients of the respective stations turned out to be higher than those. of the monthly trend of all stations, contrary to DAVIES' result (1965) on West Africa.
Average and reduced atmospheric trasparency (t) as calculated by the equation tm=a+b (where m denotes the mean optical air mass of respective latitude) turned out to be 0.79, which appears to be smaller than the value 0.83 of the previous paper of other authors. But when the difference of sensitivity between the two types of sunshine recorder i. e. of the Jordan type and the Campbell-Stokes type, is taken into, account and recalculated, it increased to 0.83, just the same value of previous papers. Thus it is pointed out that 'different sensitivity between different types of sunshine recorders may be important in this sort of calculation.
The mean values of a and b in Japan turned out to be 0.22 and 0.52respectively by the Jordan sunshine iecordei while they became 0.22and 0.57 after the correction corresponding to the Campbell-Stokes sunshine recorder.
