The purpose of this study is to present the meso-scale distribution of productivity of agricultural land (P. A. L.) in Japan and its change during the period from 1960 to 1975.
P. A. L. is defined as gross product (thousand yen) of agriculture per agricultural land. The gross product of processed agricultural products were, however, excluded from the figure. The data for gross product of agriculture are obtained from the statistics on the agricultural income published by the Ministry of Agriculture, Forestry and Fishery. The book includes the amounts of products such as rice, wheat, barley, other cereals, peas, beeps, potatoes, sweet potatoes, vegetables, fruits, industrial crops, flower, sapling, and livestock. Agricultural lands includes cropland, orchard, pasture, and grassland pasture. These data for the analysis in 1960, 1965, 1970 and 1975 are taken from the Agricultural Census of Japan.
The study area covers entire Japan excluding Okinawa prefecture due to the unavailability of data. The whole area is divided into 305 unit districts (Fig. 1), general nature of which were fully examined by Birukawa et al. (1964).
The first step of the analysis was the preparation of maps of P. A. L, in each year. Then, the change of cereal distributions of P. A. L. were investigated by comparing these series of maps one another.
Subsequently, the polynominal trend surface analysis was applied for analyzing the general distribution pattern and the change from 1960 to 1975. The general pattern of P. A. L. for each polynominal degree in each year, was also analyzed. In addition, the general patterns of P. A. L, were classified into types, and the residuals were considered as local components.
The maps of standardized P. A. L. shows high scores in the fringe area of the metropolitan areas facing the Pacific Ocean and areas facing the Inland Sea, while low scores are in the several areas in the remote and secluded districts of Hokkaido, and the areas facing the Japan Sea (Fig. 2). It is clear that the difference in scores between the districts facing the Pacific Ocean and those facing the Japan Sea increased from 1970 to 1975.
The number of areas with very high score increased significantly from 1965 to 1970. As a result, the number of districts with very high score is twice as numerous in 1970 compared to 1960. The increasing rate of areas with high score has been gradually getting higher. The number of districts with medium score decreased drastically from 1965 to 1970, and this tendency continued untill 1975. On the other hand, districts with low score gradually increased in number. Thus in 1975, there are 33 additional districts with lowscore compared with 1960. Regional variation of standardized P. A. L, has decreased in the recent census (Fig. 3). The types of change of P. A. L. gradually increased in number during this period, and the patterns of the change have been diversified.
Fig. 4 shows the fitness of the trend surface to P. A. L.. There is a tendency of gradual increase of fitness from the first to the fifth degree in each year of analysis. Except for 1960, the fitness decreases at the 6th degree, and sharply increases in the 7th degree. Judging from maps of each year, the fitness in 1965 generally showed the low percentage, while the percentage were high in 1970.
Comparing the results of variance analysis (Table 1) with the change of fitness of P. A. L., the general distribution patterns are investigated in this paper, at the 8th degree for 1960, and at the 7th degree for the remaining 3 census years (Fig. 5).
The inspection of this figure shows the regions of maximum on the trend surface extending from Osaka to eastern and southern Shikoku, and from Tokyo to Shizuoka prefecture, and the region centered around Akita.

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Microclimatological observations were carried out in order to make clear the formation of the ground inversion on the mountain slope accompanied with rapid decrease of net radiation before and after sunset. The observations were made on the northeastern slope of Mt. Omatsu (1, 648.7 m) in the northern part of Nagano Prefecture, during the period from July 29 to August 1, 1978. Seven points for observation were selected on the slope between about 1, 250 m and 1, 450 m a. s. 1. The horizontal distance is about 1, 600 m, between the highest station No. 1 (1, 450 m) and the lowest No. 7 (1, 250 m) and the average inclination is approximately 7°. Net radiation measured by economical net radiometer or net radiometer, wind speed and direction by photo-electronic wind vane and anemometer at the height of 1.0 m above the ground, and air temperature and relative humidity by Assmann ventilated psychrometer at the height of 1.3 m and 0.3 m above the ground were observed every 2 minute during the nights from July 29 to August 1, 1978. The difference of air temperature between two levels is defined as “the degree of inversion ”. Furthermore, the difference of temperature falling between two levels is defined as “the vertical difference of cooling”.
The results of the observation are summarized as follows: (1) “The degree of inversion” on the slope of Mt. Omatsu before and after sunset correlates negatively with the net radiation at stations No. 3 (1, 320 m) and No. 5 (1, 275 m). On the other hand, the correlation at station No. 7 has a positive slope. (2) Maximum. value of temperature falling at the height of 0.3m was observed at station No. 3 for two and half hours from 17 h 30 m to 20 h 00 m, and it was at stations No. 3 and No. 5 that the temperature falling was recorded greater at the height of 0.3 m than at the height of 1.3 m. (3) During the time from 17 h 30 m to 20 h 00 m, “ the vertical difference of cooling ” which was calculated every 30 minute varied slightly within a range from -0.2°C to 0.0°C at stations No. 1 and No. 2. Furthermore the value at station No. 7 fluctuated largely from positive to negative, and again to positive value. From these facts it is considered that cooling of the surface boundary layer is disturbed by the advective air from outside of the slope. On the other hand, it indicates the high positive value (max 0.5°C) on the slope from stations No. 3 to No. 5, where the surface boundary layer is considered to be cooled due to the infrared radiation from lower layer. These results nearly agreed with the observation result which was carried out on the same slope of Mt. Omatsu, August 20, 1976 (Nakamura, 1978).
These considerations lead to the conclusion that in the area ranging from station No. 3 through No. 5, the lower part of the slope of Mt. Omatsu, the ground inversion developed strikingly before and after sunset.

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Based on the suggestion by R. A. Bagnold that the normal probability idea firmly associated with sand size distribution must be revised, the present author attempted to examine grain size distribution of sediment in transit: wind blown sand and water driven sand. The samples of blown sand were collected by trapping sand grains which had cleared the brink and fallen on the slip-face of a typical dune on the Nakatajima Coast, facing the Pacific Ocean. The samples of water driven sand were collected in the Shinano River just downstream of the junction with a main tributary, the Uono River; the collection work was conducted using a hand-made sampler lowered down from a boat during a small flood due to melting snow.
Grain size analysis of the samples collected was carried out using a settling-tube measuring system installed at the Institute of Geoscience, University of Tsukuba. Results of the analysis are plotted in Fig. 2 (wind blown sand) and Fig. 3 (water driven sand). These two figures show that each of the analyzed samples contains sand-particle population and, except a few samples of blown sand, admixes finer-particle population.
The sand-particle population shows conspicuous regularity in grain size distribution. The points of this population align along the two asymtotes (Figs. 2 and 3); this suggests that the grain size distribution may follow the log-hyperbolic distribution. However, there still remains the possibility that the grain size distribution belongs to the log-normal one. The author, then, examined this possibility applying the following method.
At first, the size frequency data were plotted on normal probability paper (Fig. 4-A), and its phi-mean M_ψand phi-standard deviation σ_ψ. were obtained. For the case of samples admixed finer-particle population (Fig. 4-B), the sand-particle population was properly partitioned of from the finer-particle population by the method previously described (Inokuchi, 1977). Based on the values of M_ψ and σ_ψ, theoretical log-normal curves were drawn as dotted line in Fig. 5 for each sand-particle population except Nos. 1001 and 1002. In this figure in which size classes finer than 3_ψand or 3.5_ψand are not plotted, the original points seem to fit fairly well to the dotted curve, except size classes around 3_ψand which may be affected by grains belonging to finer-particle population. However, a comparison of Figs. 2 and 3 with Fig. 5 indicates that the grain size distribution of the sand-particle population belongs to the log-hyperbolic distribution rather than the log-normal distribution.
According to Bagnold (1953), the slope of the coarser wing is denoted by C, and that of the finer wing by S. Their values are shown in Table 3. For all the samples of wind blown sand, C is nearly equal to S, and for the samples of water driven sand, C > S. However, taking into account the effect of admixture of grains originally belonging to finerparticle population on size classes around 3tp, the proper slopes of sand-particle population may also be C _??_ S for water driven samples.
It is found that values of C are not at random through all the samples but are grouped into discrete classes, and that there exists a definite ratio between average values of individual classes (Table 3).

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