Stalagmite and Marine Sediment Records: Land-Sea Paleoclimatic Correlation in East Asia

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Project title

Code/計畫編號

NSC97-2116-M019-003

Translated Name/計畫中文名

石筍與海洋沉積物記錄---東亞海陸古氣候連比

Project Coordinator/計畫主持人

Min-Te Chen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=1676996

Year

2008

Start date/計畫起

01-08-2008

Expected Completion/計畫迄

01-07-2009

Bugetid/研究經費

510千元

ResearchField/研究領域

地球科學

"基於冰心與北大西洋海洋岩心的古氣候記錄顯示最近十萬年地球的氣候除了表現出軌道時間尺度變化外，另間歇出現千年至百年時間尺度的週期或事件（冰段與間冰段變化、漂冰碎屑事件）。熱帶西太平洋與東亞的氣候在這時間尺度上是如何反應或與高緯氣候變化交互影響仍是目前古氣候學需解決的問題。本計畫將利用近年來國際海洋古全球變遷與海洋鑽探計畫在熱帶西太平洋所取得得海洋岩心，與東亞的高解析度石筍古氣候記錄，以了解高緯氣候變化在西太平洋與東亞的衝擊與海陸氣候事件的連繫。本計畫將分析東海與南海的岩心記錄的最近十萬年的海水表面溫度與鹽度變化，並研究海洋表層溫鹽變化與葫蘆和董歌洞石筍記錄的降雨/乾旱變化的關連。本計畫將分析海洋岩心浮游有孔蟲殼體的鎂鈣比，作為海水表面溫度變化的代用指標，並用浮游有孔蟲的氧穩定同位素，再扣除海水表面溫度與海水面升降變化的效應後，解釋其殘差為海水表面鹽度的代用指標。初步分析結果顯示最近一萬六千年的東海，在高緯氣候發生漂冰碎屑事件時，海水表面鹽度增加，並可連比同時的東亞陸域乾旱事件，指示出本區域可能容易受到東亞夏季季風減弱所產生的降雨量減少所帶來的氣候衝擊。本計畫亦將利用最新的大氣海洋耦合模式所模擬的在漂冰碎屑事件發生時期，大西洋溫鹽環流停滯所產生西太平洋與東亞氣候的水文循環變化，來比較本研究的古海洋與古氣候資料。" "Paleoclimatic records of ice cores and North Atlantic marine cores show that the last 100 kyr climate changes of the globe are dominated by orbital variations but interrupted by millennial to centennial-scale cycles or events (Dansgaard-Oeschger cycles, stadials and interstadials) or events (Heinrich events, Ice Rafted Debris events). It is still not fully understood how the tropical western Pacific and East Asia have been interacted with such global climate changes over the time scales. Recent IMAGES and ODP expeditions in the western Pacific have retrieved a much full-array of paleoceanographic evidence, in conjunction of high resolution stalagmite records from East Asia, that now provide the opportunity to advance our understanding on the climatic impacts and linkage of lands and seas. The proposed research here aims to analyze ~100 kyr records of sea surface temperature (SST) and sea surface salinity (SSS) estimated by multi-proxies of marine sediment cores retrieved from the East China Sea (ECS) and South China Sea (SCS), and assess their correlations to precipitation/aridity records of Hulu and Dongge cave stalagmites. We propose to measure high resolution Mg/Ca data from planktic foraminifers as SST indicators of the ECS and SCS cores, and use these SST to remove the temperature components of planktic foraminifer oxygen isotopes from the same cores, and interpret the residual of the isotopes as SSS indicators after further removing sea level influences on the foraminiferal isotopes. Our initial analysis based on a short SSS record of the ECS of the past 16 kyr indicates more saline surface water conditions coincide with more arid conditions on land in East Asia during Heinrich events, suggesting a possibly linkage of precipitation changes driven by East Asian monsoon in this region. The impacts of hydrological changes in the western Pacific and East Asia during the millennial-scale events will be compared to new-version modeling results from fully coupled ocean-atmosphere GCMs that simulate global climate impacts from the shutdown of Atlantic thermohaline circulation."

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Stalagmite and Marine Sediment Records: Land-Sea Paleoclimatic Correlation in East Asia

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