Climatic Division of Japan (4)

Abstract

In 1928, the author published in this journal a preliminary paper on the same subject as this one. During the five years that have since elapsed, additional observations have been made and fresh data obtaid. All of which have enabled him to make better determinations of the climatic provinces of Japan. In the previous paper, for example, he established two sorts of provinces, based on characteristic types of annual temperature march and seasonal variations. In this paper, however, he has attempted to determine only one kind of climatic province, instead of two, as he had done previously. Although the above mentioned two elements are still the most important, all the climatic elements have been taken into account. The otherr elements, such as relative humidity, amount of cloud, evaporation, etc., are rather subordinate, their seasonal variation having nearly the same character as that of temperature and precipitation. Now, the climate of Japan differs markedly according to latitudes and also withh the prevalence or otherwise of monsoons; for the Japanese Islands extend from north to south for a great distance, which accounts for the remarkable difference in air temperature in the islands. At the same time, however within the Islands, the land forms are not uniform and monotonous as in the neighbouring continent, but comprise lofty mountain chains of various altitudes that form a climatic divide between the regions on either side of it. The monsoonal rain is highly influenced by this topography, so that the Pacific side and the Japan Sea side of the central mountain chain of the Japanese mainland show remarkable contrast in their seasonal variation of precipitation. The minute topography also influences the type of rainfall, which affords a suitable basis for classifying into minor climatic divisions. We have here taken the above two elements, temperature and precipitation, which are influenced by latitude and land forms, respectively, as the fundamental basis for dividing Japan into climatic provinces. The former is used for the primary and the latter for the secondary and tertiary divisions. Thus in the primary classification, the whole of Japan is divided into the following three parts: Northern Japan, the coldest region in Japan in which for at least four months, the mean temperature is below 0°C. Central Japan, where the most moderate climate prevails, and the mean annual temperature is lower than 20°C. Southern Japan, with a mean annual temperature higher. than 20°C. The boundary between Northern and Central Japan is the Tugaru Strati and that between Central and Southern Japan the Collet Strait, north of the Looc hus, as shown in. Fig. 2. These three parts are again divided into 10 provinces (secondary divisions), 26 regions and 36 sections (tertiary and its subdivisions). The small areas that show local contrast of climate from the surrounding districts are distinguished as localities. These provinces, regions, and sections, with their climatic characters are as follows, Northern Japan. (A) Karahuto (S. Sakhalin) Province. The coldest region in Japan. For five months the mean temperature is lower than 0°C. Precipitation is not abundant together with northern Korea. It is the driest part of Japan. Aa E. Karahuto Region. Colder and wetter than Ab. Surface waters of the Terpienya Bay change into sea-ice. The Sikka Locality has severe winters and cool summers. Its annual mean temperature is lower than 0°C. Ab W. Karahuto Reg. Warmer but slightly drier than Aa. (B) Hokkaido Pr. In this province, which includes the Kurile Islands, during four months the mean temperature is lower than 0°C. Bc W. Hokkaido Reg. Warmer and more abundant precipitation than Bd, especially in winter. Considerable snow accumulates. Cloudy weather prevails in winter, as on the western side of the Japanese mainland.