open access

https://hdl.handle.net/2115/20462

Rapid fluctuations in alkenone temperature in the southwestern Okhotsk Sea over the past 120 kyr

日本語

2007-03-23

北海道大学低温科学研究所

Low Temperature Science

65

115-122

2章 千年～10万年スケールの気候復元とモデリング

To better understand the way in which changes in the surface environmental in the Okhotsk Sea influence climate change in East Asia,we estimated sea surface temperatures in the southwestern Okhotsk Sea for the past 120 kyr at millennial to centennial temporal resolution using a long-chain unsaturated alkyl ketone (alkenone) thermometer. The alkenone temperature, which corresponds to the SST to 20 m depth in autumn, showed repeated abrupt changes at a centennial timescale, especially during the last glacial period at 20-60 kyr before present (BP). The alkenone temperature changed in tan dem with changes from interstadials (warm events) to stadials (cold events) recorded in the δ^{18}O record of ice cores recovered from Greenland. Anomalously high alkenone temperatures occurred repeatedly during the glacial period. These warm alkenone-temperature episodes probably had multiple causes: (1) the main season of alkenone production may have shifted from autumn to midsummer over the course of the glacial period because of the expansion of sea-ice coverage to nearly all seasons except midsummer; (2) related to the expansion of the sea-ice season, the sea-ice melting season may have shifted from spring to summer and sea-ice melting during summer might have led to stratification of the surface water, resulting in a high SST; and (3) an active Asian summer monsoon may have contributed to warming the surface waters of the southwestern Okhotsk Sea. In combination, these effects could have generated anomalously high alkenone temperatures in the southwestern Okhotsk Sea during the examined glacial period.

紀要論文

Version of Record

1880-7593

AA12122962