北海道石筍指示之過去十一萬至七萬年中低緯度間海洋與大氣遙相關紀錄

Abstract

聖嬰/南方震盪是全球海洋與大氣最顯著的變動模式之一，現代觀測結果指示發生在低緯度赤道太平洋的聖嬰/南方震盪與阿留申低壓之間具有遠距離的海洋與大氣遙相關，然而這樣的現象是否在千年的時間尺度之下亦有發生，目前尚未有確切的觀察數據。北海道地區的降雨受控於阿留申低壓影響，因而本研究採集了北海道地區洞穴(43°14’12” N, 142°13’09” E)中生長於十一萬兩千年至七萬兩千年之間的石筍，並利用其碳同位素與微量元素鎂、鍶和鋇之組成，重建了當時的降雨紀錄。結果顯示在千年尺度下，北海道降雨與東、西部赤道太平洋之間的海水溫度異常有共同變化的趨勢，代表在過去本時間段之中，阿留申低壓狀態的改變與太平洋赤道地區的海水溫度變化有遙相關性，彰顯低緯度與中緯度地區海洋與大氣環境遠距離連結的重要性。

El Niño–Southern Oscillation (ENSO) is one of most important global climate modes. In modern day, an ENSO-Aleutian Low (AL) teleconnection was suggested. Whether similar teleconnection had occurred over a multi-millennial scale is not yet available. Here, we present stalagmite-inferred hydroclimate records covering the interval of 112 - 72 ka (kiloanni, age before 1950 C.E.) from Oku-Ashibetsu cave in Hokkaido (43°14’12” N, 142°13’09” E), northern Japan, where the rainfall pattern is influenced by the AL. Records of the stalagmite δ13C, a proxy reflecting changes in temperature and precipitation, covary with the trace elements (Mg, Sr and Ba), proxies for hydrological variation. During 112 - 72 ka, millennial scale covariation was found between the proxies-inferred Hokkaido regional precipitation and the Pacific long-term ENSO-like states reconstructed by the marine sediments. Our results suggest that the hydrology in the western Hokkaido region is possibly coupled with Pacific Ocean hydrodynamics via the AL, emphasizing the teleconnection between low and mid latitudes in the past.