| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
The reconstruction of climatic conditions during the Little Ice Age was attempted, based on old documentary records. There are many old documents in which daily weather conditions are recorded. Those records were collected and arranged according to date. Througth the works, weather diagrams were compiled for the historical times in Central Japan. By analyzing the diagrams, some climatic conditions during the historical times (from the end of the 18th century to the middle of the 19th century) were reconstructed for Central Japan. The main results are shown as follow. (1) Winter season temperature was very low in the 1810s and 1820s. After the period, it tends to warmer gradually. (2) Precipitation amount in winter on the Pacific coastal region is small. But after the 1830s, it increases to the level of the present. (3) Frequency of appearance of the winter monsoon type flow pattern was hgher in the 1810s and 1820s. It becomes lower in the 1830s. (4) The end of the Bai-u season was delayed in the 1780s, 1830s and 1890s. In those periods, cool summers appeared in northern Japan frequently. (5) Heavy rainfalls frequently occur in the Bai-u season in the middle of the 19th century. On the contrary, rainfall amount during the Bai-u season was very small in the beginning of the 19th century. (6) Climatic condition of summer season was dry with little rain in the beginning of the 19th century. Conversely, it is wet and much rain in the middle of the 19th century.
There were some differences in climatic conditions between the early period and the middle period of the 19th century. The main causes that bring the differences may be due to the changes of the general circulation over the East. Asia.
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