[M-IS03] Evolution and variability of the Asian Monsoon and Indo-Pacific climate during the Cenozoic Era

[MIS03-P04] Low to mid-latitude sea surface temperature change and its latitudinal gradient in the western North Pacific through glacial-interglacial cycles.

*内田 貴之¹、久保田 好美²、堀川 恵司³、村山 雅史⁴、佐川 拓也⁵ (1.金沢大学大学院. 地球社会基盤専攻、2.国立科学博物館、3.富山大学. 学術研究部理学系、4.高知大学. 農林海洋科学部海洋資源科学科　、5.金沢大学理工研究域)

キーワード：西太平洋暖水塊、海洋表層水温、浮遊性有孔虫、Mg/Ca

Western Pacific Warm Pool (WPWP) holds the warmest surface water on Earth. Therefore, it is an essential heat and water vapor source for atmospheric circulation and influences global climate. However, it is unclear how the extent of the WPWP changed in response to glacial-interglacial cycles due to the lack of sea surface temperature (SST) reconstructions in the subtropical western Pacific, especially with no reconstructions within the subtropical gyre. In this study, we investigate the orbital-scale variability of the SST gradient in the tropical-subtropical western Pacific. We use piston cores KH92-1 3aPC retrieved in the West Caroline Basin (8°00.94′N, 139°38.41′E) and KH-22-7 OP-01 retrieved in the West Mariana ridge (16°45.216’N, 143°03.269’E ). The former is within the WPWP, while the latter is within the subtropical gyre. SSTs are reconstructed by Mg/Ca of planktic foraminifera, Globigerinoides ruber, for the last 300 kyrs. Over the past 300 kyrs, the glacial-interglacial amplitude in SST is 3–4 ºC in the tropics, whereas it is 4–5 ºC in the subtropics. We will further discuss temporal changes in the latitudinal SST gradient covering from the equator to 32°N by compiling published data.