[M-IS34] Paleoclimatology and paleoceanography

[MIS34-P14] Relationship between early summer precipitation in Japan and the El Nino-Southern Oscillation over the past 400 years

*Wataru SAKASHITA¹, Yusuke YOKOYAMA¹, Hiroko MIYAHARA², Yasuhiko T. YAMAGUCHI³, Takahiro AZE¹, Stephen OBROCHTA⁴, Takeshi NAKATSUKA⁵ (1.Atmosphere and Ocean Research Institute, The University of Tokyo, 2.College of Art and Design, Musashino Art University, 3.Department of Earth and Planetary Science, The University of Tokyo, 4.Faculty of International Resource Sciences, Akita University, 5.Research Institute for Humanity and Nature)

The El Niňo-Southern Oscillation (ENSO) potentially influences East Asian Summer Monsoon (EASM) rainfall, but the relatively short instrumental rainfall record hinders the progress of a longer-term understanding of this relationship. To partially overcome this issue, we reconstruct precipitation from tree-ring oxygen isotopes (δ¹⁸O) in central Japan from AD 1612 to 1935. Our results show that tree-ring cellulose δ¹⁸O is significantly correlated with May-June (MJ) rainfall in central Japan, allowing us to examine the relation between the EASM summer rainfall and ENSO during the past 400 years. Time- and frequency-domain comparison of the tree-ring δ¹⁸O record and recent ENSO reconstructions show a common high-frequency (3-8 year) variability that characterized the mid-17th, late 18th and late 19th centuries. Similar analyses of instrumental MJ precipitation and several ENSO indexes during the 20th century reveal that this high-frequency oscillation reappeared from AD 1980. Comparison of ENSO and Pacific Decadal Oscillation (PDO) indexes reveals that the ENSO-EASM relationship is strong when ENSO variance is high, and the PDO phase may modulate the ENSO-EASM relationship over the past four centuries.