지난 최대 빙하기 이후 쿠로시오 난류 확장역과 중앙적도태평양 해역의 원격상관성

Abstract

Changes in relative sea surface temperature (SST) were reconstructed from planktic formaminiferal assemblages since the last glacial maximum (LGM) in order to understand responses of the Kuroshio extension (KE, 32ºN, 158ºW, 2500 m depth)and central equatorial Pacific regions (CEP, 7ºN, 177ºW, 3409 m depth) to a stadial (Younger Dryas, YD) and two interstadial (Bølling-Allerød, B-A, and mid-Holocene, MH) events. The result reveals the opposite responses of two regions.The KE cooled at YD and warmed at B-A and MH events, which likely resulted from the southward and northward migrations of the Kuroshio-Oyashio front on differential Northern Hemisphere (NH) cooling and warming, respectively. On the contrary,the CEP cooled at the B-A and MH and warmed at YD. Our results suggest atmospheric teleconnection between two regions, in which NH thermal forcing leads to the changes in latitudinal position of Kuroshio-Oyashio front as well as the reorganization of climate state in the tropics. We postulate that the southward advance of the westerlies by differential NH cooling pushed the Kuroshio-Oyashio front southward and resulted in cooling of KE region. Simultaneously, the migrationofthe convection center of the Hadley Cell (Intertropical Convergence Zone, ITCZ) toward equator led to weakening of southeast Trades, which in turn reduced equatorial upwelling. A series of these processes results in weakening of zonal SST gnd central equatorial Pacific regions (CEP, 7ºN, 177ºW, 3409 m depth) to a stadial (Younger Dryas, YD) and two interstadial (Bølling-Allerød, B-A, and mid-Holocene, MH) events. The result reveals the opposite responses of two regions.The KE cooled at YD and warmed at B-A and MH events, which likely resulted from the southward and northward migrations of the Kuroshio-Oyashio front on differential Northern Hemisphere (NH) cooling and warming, respectively. On the contrary,the CEP cooled at the B-A and MH and warmed at YD. Our results suggest atmospheric teleconnection between two regions, in which NH thermal forcing leads to the changes in latitudinal position of Kuroshio-Oyashio front as well as the reorganization of climate state in the tropics. We postulate that the southward advance of the westerlies by differential NH cooling pushed the Kuroshio-Oyashio front southward and resulted in cooling of KE region. Simultaneously, the migrationofthe convection center of the Hadley Cell (Intertropical Convergence Zone, ITCZ) toward equator led to weakening of southeast Trades, which in turn reduced equatorial upwelling. A series of these processes results in weakening of zonal SST g