The Kanto Plain is situated at Central Honshu facing the Pacific Ocean, its topography being shown in Fig. 1. In this area and its surroundings we have about 170 climatological stations, where daily minimum- and maximum temperature are observed. Using these temperature data, the author prepared from December 1957 to November 1958 one round year's daily minimum- and one colder half year's daily maximum temperature distribution patterns amounting to 547 sheets in all. The scale of the base map is 1:1, 000, 000. On the warmer half year's maximum temperature distribution patterns, he has already reported on the previous paper in this series.
After comparative study of these patterns, he classified minimum temperature patterns into four types, which were considered to be interesting from the standpoint of meso-climatology. Typical patterns of these four types are described under the head number 2•1, 2•2, 2•3 and 2•4, and shown in Fig. 3, 4, 6, 7, 9, 10, and 12. At the bottom of these figures, self-recorded temperature curves at local meteorological observatories are also shown. According to the similarity of the patterns, ten typical patterns are selected for each of the four types. Table 2 shows the dates and wind condition for these 40 days.
In order to clarify the discontinuity zone which appeared on the patterns, the author drew dot maps, i. e. Fig. 5, 8, 11 and 13. The method employed is as follows; 1) 5-km interval orthogonal mesh was covered on the temperature distribution patterns, 2) number of 1°C interval isotherms crossing over these 5-km squares were counted, 3) ten days total was calculated for each spuare, and expressed by a dot whose area is proportional to the number of the isotherms crossing the square.
Daily maximum patterns are classified into two types. They are described under the head number 3•.1 and 3•2, their typical patterns are shown in Fig. 14 and 16. For the former type the same procedure was taken for drawing mean dot map (Fig. 15).
Land surface of the Kanto Plain is fairly flat and environment of climatological stations are considered nearly uniform. If entire area is satisfied with the same climatological condition, no areal difference on temperature distribution is expected. Thus the main reasons for causing the development of various distribution patterns are considered to be the temperature gradient between land and sea and the wind system from a different origin.
The author collected water temperature data at the sea surface and constructed Fig. 17, where full line ‘To’ denotes coastal sea surface water temperature at Tomisaki and broken line ‘TB’ denotes Tokyo Bay's surface water temperature near Haneda, both data are representative within the range ±1°C. In the figure, a cross stands for the daily minimum- and a small circle represents the maximum temperature at inland station, Kumagaya. The dates of above-mentioned six types of distribution patterns are also indicated by different marks, so we can judge from these figures that in which season and on what land-sea temper ature condition these patterns are liable to appear. Brief description of the characteristics of the six patterns are as follows;
2•1 type: This type of pattern appears on a clear and weak NW winter monsoon night, when the sea water temperature is warmer than the inland minimum temperature. In this case a warmer belt appears along the coast and a part of inland, which coincides with the area with a fairly strong wind. On the clear night with a strong monsoon, areal difference of temperature is not so conspicuous (Fig. 2).
2•2 type: When the cold front is staying along the Pacific coast of Honshu, SW- or NE-wind becomes, stronger and blows through south-eastern part of the Kanto Plain. In this case coastal area becomes warmer and inland area colder, and clear discontinuity zone appears between them.