TY - JOUR
T1 - High-Resolution Evidence for Middle Holocene East Asian Winter and Summer Monsoon Variations
T2 - Snapshots of Fossil Coral Records
AU - Asami, Ryuji
AU - Yoshimura, Natsumi
AU - Toriyabe, Hiroto
AU - Minei, Shogo
AU - Shinjo, Ryuichi
AU - Hongo, Chuki
AU - Sakamaki, Takashi
AU - Fujita, Kazuhiko
N1 - Funding Information:
We acknowledge anonymous reviewers for their comments. We thank H. Adachi and N. Nosaka (Geoact Co. Ltd.) for help with core sampling and R. Uemura, M. Chinen, and Y. Akamine (University of the Ryukyus) for help with experiments. This research was supported by the Japan Society for the Promotion of Science (JSPS), KAKENHI (Grant Nos. 26550012, 26707028, and 18K18522 to R. A. and 25340060 to K. F.) and the NEXT Program (Grant No. GR083 to T. S.).
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/8/28
Y1 - 2020/8/28
N2 - We first generated 53-, 4-, 10-, and 9-year-long bimonthly time series of oxygen isotopes (δ18O), Sr/Ca, and U/Ca from 4.4 and 4.9 ka corals in Okinawa, Japan. Results indicate that the mid-Holocene sea surface temperature (SST) and seawater δ18O were <1°C lower and 0.1–0.2‰ higher than today. Spectral analyses of reconstructed SST and seawater δ18O time series revealed East Asia monsoon (EAM) and El Niño/Southern Oscillation (ENSO) variations. Moreover, the latter had a dominant component of decade-scale hydrologic variations. The Sr/Ca and U/Ca variations with removal of the ENSO component showed larger fluctuations by ~2°C in winter and ~0.6°C in summer at 4.4 ka relative to today, demonstrating (slightly) greater influences of the EAM variation on the northwestern subtropical Pacific in winter (summer) at that time, which are probably caused by enhancement of the EAM intensity and/or a southward migration of the latitudinal circulation.
AB - We first generated 53-, 4-, 10-, and 9-year-long bimonthly time series of oxygen isotopes (δ18O), Sr/Ca, and U/Ca from 4.4 and 4.9 ka corals in Okinawa, Japan. Results indicate that the mid-Holocene sea surface temperature (SST) and seawater δ18O were <1°C lower and 0.1–0.2‰ higher than today. Spectral analyses of reconstructed SST and seawater δ18O time series revealed East Asia monsoon (EAM) and El Niño/Southern Oscillation (ENSO) variations. Moreover, the latter had a dominant component of decade-scale hydrologic variations. The Sr/Ca and U/Ca variations with removal of the ENSO component showed larger fluctuations by ~2°C in winter and ~0.6°C in summer at 4.4 ka relative to today, demonstrating (slightly) greater influences of the EAM variation on the northwestern subtropical Pacific in winter (summer) at that time, which are probably caused by enhancement of the EAM intensity and/or a southward migration of the latitudinal circulation.
KW - East Asian Monsoon
KW - Sr/Ca and U/Ca
KW - fossil coral
KW - middle Holocene
KW - oxygen isotope composition
KW - sea surface temperature
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U2 - 10.1029/2020GL088509
DO - 10.1029/2020GL088509
M3 - Article
AN - SCOPUS:85089936313
VL - 47
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 16
M1 - e2020GL088509
ER -