Recovery of 19th century Tokyo/Osaka meteorological data in Japan

We have recovered instrumental temperature and pressure observations from Tokyo covering the periods 1825–1828, 1839–1855, and 1872–1875; from Yokohama covering the periods 1860–1871 and 1874; from Osaka covering the periods 1828–1833 and 1869–1871; and from Kobe covering the periods 1869–1871 and 1875–1888. The newly recovered records contain data before the 1870s, which is a period where, until recently, no instrumental data in Japan were believed to exist. Their addition to the previous backward extension of Japanese series, as based on the recently recovered intermittent Dejima/Nagasaki series 1819–1878, implies that the nineteenth-century extension of the Japanese instrumental record no longer contains major temporal gaps. The recovered data were used for a preliminary calculation of the west-Japan temperature (WJT) series, which is a representative temperature series for the area. The existence of a warm epoch in the 1850s over W-Japan and a downward temperature trend till the early twentieth century, as previously inferred from documentary data, is confirmed from the WJT data. The pressure data implies that the temperature differences between the nineteenth and twentieth centuries are at least partly caused by a change in atmospheric circulation.