Climatic variations for the last 300 years based on the meteorological data and the historical weather records at Nagasaki

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Official meteorological observations in Japan started in 1872. Prior to that period,from 1700 onward until 1868, daily visual weather reports are documented in diaries at many places in Japan. In this study, we have recovered instrumental observations from Dejima (Nagasaki), taken under the responsibility of the Dutch, covering the periods 1819-1828, 1845-1858 and 1871-1878. The Dejima series overlaps by six months with the modern Nagasaki Observatory series 1878-present and overlaps in its pre-1871 part with the Nagasaki 1700-1868 documentary series. The recovered data provide a means for calibrating the documentary series and extend the start of the instrumental Nagasaki series back from 1878 to 1819, leaving major gaps during 1829-1844 and 1859-1871.Our final objective for this study is to reconstruct the 300 years temperature variations based on both instrumental data and diary weather records. As an example, we reconstructed a January mean temperature series at Nagasaki since 1700. The result shows the existence of apparent warmer period in 18th century compared to 19th century. Further investigations would be expected to clarify the overall feature of the climatic variations in Japan for the last 300 years.