[A-AS08] Multiple scale structure and their interactions in Asian monsoon system

[AAS08-06] Meteorological changes observed from the ground surface: an analysis of the village headman's diary of Takahama, Amakusa, facing the East China Sea,1793-1818

*Satoshi Murayama¹, Terao Toru¹ (1.Kagawa University)

Keywords:Multiscale climate variability, Perception of disasters, Sub-daily weather variability, Reconstruction of historical weather, Daily weather records in Asia

Amakusa islands in Kyushu are belonging to southwestern Japan facing the East China Sea. They are strongholds of typhoons and severe rains. However, in terms of agricultural damage, we were able to confirm that flooding was not occurred in the top season of typhoons, but the heavy rain especially during the rainy season had caused enormous flood damage. In addition, it was understood that the concern about the lack of rainfall all the time, suggested by rain seeking rituals, was worried because the number of years for which such rituals was performed exceeded 70% of the years within the observed years. Furthermore, it was confirmed that 1. sunshine was expected in July and prompt rainfall also expected at the same time as securing the amount of solar radiation accompanied by fine weather in August, and 2. rhythm and balance of rainfall amount and solar radiation amount were important for growth of rice. This importance of rhythm and balance of the weather, relatively homogeneous dependency on seasonal precipitation patterns, could be observed from detailed narratives of daily weather changes in the diaries of the village headman, Yoshiuzu Ueda. In the 25 years between 1793 and 1818, the period covered by the diaries examined in this paper, the latter part of the diary tends to be more detailed in its description of the weather than the first half, which may provide a clue to the correlation between daily and monthly weather changes. Usually, the description is as simple as clear sky and north wind, but it can also be cloudy, northwest wind, evening rain, and heavy rain around midnight on June 25, 1799 (July 27 on the solar calendar), or rainy, west wind, and sometimes heavy rain on June 14, 1816 (July 8 on the solar calendar). Daily changes in weather are accompanied by convection, reflecting surface processes and land/sea distributions, and occur near the surface on a small scale. In Ueda's diary, not only meteorological information, but also floods, droughts, and crop damage are recorded in detail, which can be observed on a longer time scale than daily changes. The problem of how to reproduce these daily changes is the subject of this paper.