[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.

*Takayuki Uchida¹, Yoshimi Kubota², Keiji Horikawa³, Masafumi MURAYAMA⁴, Takuya Sagawa⁵ (1.Graduate School of Natural Science and Technology. Kanazawa University , 2.National Museum of Nature & Science, 3.Faculty Science, Academic Assembly. University of Toyama, 4.Faculty of Agriculture and Marine Science. Kochi University, 5.Institute of Science & Engineering. Kanazawa University)

Keywords:Western Pacific warm pool, Sea surface temperature, Planktic foraminifera, 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.