Variation in the March Mean Temperature Deduced from Cherry Blossom in Kyoto since the 14th Century

Abstract

Changes in spring temperatures in Kyoto since the 14th century are estimated using flowering phenological data of cherry trees (Prunus jamasakura, a native species) from old records. It is shown that flowering dates of cherry trees in Kyoto are closely related to the monthly mean temperature of March. This result is obtained using the so called DTS method, which has been used to estimate the first flowering date of P. yedoensis (a horticultural species). However, in this case it is applied to estimate the full flowering date of P. jamasakura. It is shown that accuracy for both is almost the same. In this study, using this method with a reversed procedure, namely monthly temperatures for arch are estimated from full flowering dates. It is shown that for decadal means, calculated averaged March temperatures fell within 0.5°C from the actual value in the 20th century.The result shows that there were relatively cold periods around the mid-14th, early 16th and late 17th through the early 19th centuries. There were warm springs during the early 17th century. A steady warming trend starting the early 19th century continuing to the present i s noteworthy. It is attributable to both urban warming and large scale warming.