Typhoon Virginia (No. 6011) hit the western Japan on August 10-12, 1960 (Fig. 1) and brought a heavy -rainfall of more than 200mm to the Kanto area, 500km away from the central trajectory of the typhoon.
On this occasion, we made composite 48 hourly-rainfall maps of the period based on the data of 372 stations in the area of 45, 000 km² and checked them with radar echoes which were taken by two radars in Tokyo. 100 km range of the radars could cover almost all area. The coincidence of their distribution patterns were good.
1) Up to 2000 hour of August 10, scattered thunderstorm rains are observed in the northeastern parts of the plain and moderate rains of about 10mm/hr are reported from the southern mountaneous region. The real typhoon rain started at about midnight.
2) The typical distribution characteristics of this typhoon rain and the radar echoes are the existence of the three rain-bands stretching from the south to the north across the central part of the plain.
3) At the very south ends of the rain-bands, there are high mountain blocks closely located to the coast. In other words, the rain-bands stretch behind the leeside of these mountain obstacles along the strong prevailing southerly wind; the one is located at Boso peninsula east of Tokyo, the second one, the most remarkable of all, is situated at the central part of the plain behind the Izu and Hakone mountains and the last one is running in parallel to the second one at the westernmost part.
4) The rain-bands exist successively more than 15 hours (0900-2300 of Aug. 11) almost at the same locations. This depends mainly on the persistence of the prevailing southerly wind for the period converging into the center of the typhoon.
5) The formation of these rain-bands seems to be of orographic origin, judging from their distribution patterns and far-away locations from the center of the typhoon. There are no positive evidence to conclude them as structural origin of the typhoon.
6) Hourly locations and intensities of rain-bands and radar echoes seem to be influenced by the strength and direction of the prevailing wind during the period.
7) These rain-bands end at the central backbone mountain ranges of Japan and there are very little rains on the Japan Sea side area, the leeside of the prevailing southerly winds. Therefore, we may say that in a broad sense or in macro-scale viewpoint, this typhoon rain might be classified into orographic one. However, in meso-scale viewpoint the distribution patterns are fairly different. Three rainy belts running across the plain are distinguished. These are orographic rain-bands.

View full abstract

In the previous paper, the synoptic climatology of Hokkaido in the winter season was described, with regard to the detailed local weather features. In this paper, the author intended to sketch out the detailed weather distribution of the whole area of Japan according to actual weather patterns of winter monsoon, and to interpret the local and small scale weather features, applying the same method as the previous one.
Air flow patterns for each region, shown in Fig. 1, were determined as follows. Firstly, a series of the sea level weather map was classified into 5 types; Northwesterly monsoon type, northeasterly type (NE), anticyclonic type (H), cyclonic type (L) and frontal type (F). Cyclonic and frontal types were excluded from this paper. Secondly, northwesterly monsoon type was classified into 16 types according to the direction of gradient flow at 850mb surface (N, NNW, NW, WNW, etc.).
The detailed weather situations for each air flow type were illustrated in Figs. 4 and 11. Fig. 4 indicates the distribution of the percentage frequency of days with daily precipitation more than 5mm, for the northwesterly monsoon type, and Fig. 11 represents the same distribution for the northeastely air flow type. In the former type, the distribution of precipitation clearly corresponds to the topographical features and wind directions. Particularly, the condition of surface relief does not mean merely large scale mountain ranges, but relatively small scale ridges and valleys. Almost all areas of the Japan Sea side of Japan and some parts of the Pacific Ocean slope of Central and West Japan are characterized by snowy or rainy weather. The location of heavy snowfall area shifts with the change of wind direction. Moreover, special local climatic features are recognized in some parts of Japan. For example, as is shown in Fig. 5, snowy weather area occasionally crosses over the mountain divide (Ibuki and Suzuka Mts.), and spreads out into the Nobi Plain, situated in the Pacific side of Central Japan. This extension of snowfall area is affected by the climatic factors such as wind direction, wind speed, and upper air temperature (Fig. 7). Above all, the outbreak of severe cold air from continental Asia, associated with low temperature and high wind velocity, causes heavy snowfall over Japan Sea side and wider extension of snowy weather in some parts of the Pacific Ocean side.
In northeasterly wind patterns arise an asimilar distribution of weather in Central and West Japan. Namely, gloomy rainy weather condition is persistent in the coastal region of the Pacific Ocean, and snow or rain shower continues on the Japan Sea side, though a small amount of precipitation is observed.
When the Siberian High expands to and covers over Japan, weather becomes better, fine and calm.
In the winter season, these weather patterns transits from one to another as shown in Fig. 3. Percentage frequency and persistency of each air flow type are indicated in Tabs. 1 and 2. These results show that the north- westerly monsoon pattern is dominant in winter, especially in the northern part of Japan, and besides, northeasterly air flow and anticyclonic types mainly affect Central and Southern parts of Japan.

View full abstract

The authors have had limnological researches in Lake Kizaki several times since 1959 intending to make clear the movement of non-steady currents of such a small lake as Kizaki. They measured water temperature, direction and velocity of wind, and movement of “current drags” as an indicator of the movement of late currents.
The water temperature was measured by a thermister-type thermometer, wind velocity by a Robinson's cup anemometer and water movement by several current drags kept at the depths of 1, 3, 5, 7, 10 and 15 meters.
The authors inquired the distribution of water temperature at each depth as is shown Figs. 3-5, from which they presumed the water movement. Comparing this presumptive movement with that of current drags shown in Figs. 7-9, the following conclusions were reached:
The northern and southern winds which are prevailing all the year round decide the movement of nonsteady current. In the summer season, the northern wind gives more remarkable influence on the currents than the southern wind does, not because of the difference of wind velocity but because of the topography around the lake. In the autumn, the partical circulation period, the movement of currents caused by wind is indistinctly recognized.
The velocities of currents at the surface and the thermocline layer are low, while those of currents between the surface and the thermocline layers and below the thermocline layer are considerably high.

View full abstract

The Association of Japanese Geographers held a field symposium on “Geomorphic development of the drainage basins of the Kiso and the Yahagi Rivers” in October, 1963. Discussions at the symposium and the outline of the previous works on the geomorphic development of this area are summarized in this article.
The drainage basins of the Kiso and the Yahagi Rivers and the Nobi Plain which is situated along the lower course of the Kiso River show various landforms molded in different geologic ages; erosional surfaces being in mountains, depositional surfaces of the Pliocene Seto Group in the middle course of these rivers, fluvial and marine terraces of the Pleistocene along the rivers and the inner margin of the plain, and fault scarps in mountains and even on terrace surfaces. Accordingly, this area has been considered as one of the standard regions in reserch of the geomorphic history of Japan.
Although problems on correlation and process of the formation of the fluvial and marine terraces are discussed in this paper, a greater emphasis was put on the following subjects m the correlation of gravel beds of the Seto Group scattered in the whole region, the palaeogeography of the time when the Seto Group was deposited, the recognition and correlation of erosional surfaces and the process of the growth of fault scarps.

View full abstract