Solar Radiation and Duration of Sunshine in Japan

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 staAiOns 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 in 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. 52 respectively by the Jordan sunshine iecordei while they became 0.22 and 0., 57 after the correction corresponding to the Campbell-Stokes sunshine recorder.

Globalstrahlung und Sonnenscheindauer in Ostasien

“…For the application of the equation to daily values, for instance, some weighting factors may be necessary, since cloudiness may not be randomly distributed throughout the day [5,12]. Okada (see [16]) found in the five-year observations at the Central Meteorological Observatory in Japan that the Jordan recorder is about 10 per cent more sensitive than the Campbell-Stokes recorder. Global radiation has been measured by either thermopile-type instruments, such as Eppley pyranometers, or bimetallic-type instruments, such as Robitzsch actinographs; sunshine duration has been measured by either Campbell type of instruments had also been used in most Japanese stations until around 1972 when they were replaced by thermopile-type instruments.…”

“…No correction has been made in this study for such factors as cloud cover, snow, altitude, and relative humidity with the view of improving the relationship only slightly as demonstrated by Bennett [ 19] and Swartman and Ogunlade [20]. Sekihara and Suzuki [ 16] applied this value 8* for the correction of their sunshine data. In Taiwan, Hong Kong, and the Philippines, Campbell-Stokes sunshine recorders have been used to measure sunshine duration, while in Korea and Japan Jordan recorders have been used.…”

“…The Angstr6m formula was later modified by Prescott [8] to read: Q/Qa = a + b n/N, where Q is global radiation, Qa extraterrestrial solar radiation at the top of the atmosphere or the Angot value, n actual sunshine hours, N maximum possible sunshine hours, a, b empirical constants. Black et al [ 11 ] referred to the marked decreasing trend of a with increasing latitude and more or less constant b for selected stations in Europe and Australia; Glover and McCulloch [ 12,13 ] found in Africa that a and a + b decrease with latitude while b remains constant; Davies [14] also found in West Africa a rough latitudinal trend with a decreasing and b increasing northward, and showed a remarkable annual cycle of a and b as associated with the movement of ITCZ whereas Black et al [11 ]; Day [15], and Sekihara and Suzuki [ 16 ] found no evidence of systematic change in these regression coefficients with changing latitudes for the data from the world (32 stations), British Isles (16 stations), and Japan (6 stations), respectively. Y-intercept, a, in the modified equation shows a hypothetical percentage of the diffuse component (D/Qa, where D diffuse radiation) in completely overcast conditions when actual sunshine hours become zero.…”

“…Fig. Relationship of regression coefficients a and b in Q/Qa = a + b n/N to latitudes based on various reports [8,9,11,12,[14][15][16][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. This figure suggests that the relation between latitudes and regression coefficients, if any, is poor on a global scale.…”

Web-Based Decision Support System for Japonica Rice Cultivation in West Java Province, Indonesia

“…a and b are coefficients of linear regression. In Japan area, a equals 0.22, and b equals 0.57[20].Dry weight of each rice organs (stem, leaf, and panicle), and leaf area index (LAI) were observed by measuring two destructive samples selected based on the average height, average tiller number, and plant diameter on the soil surface of 10 undestructive samples. The destructive sample of rice organs were dried on an oven for 48 hours on 80 0 C. Destructive sampling was started on July 11th and it was conducted every week.…”