15万5千年の西アフリカのモンスーンと海洋の熱的進化
Syee Weldeab1, David W Lea, Ralph R Schneider
1Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106-9630, USA. sweldeab@ifm-geomar.de
まとめ
西アフリカのモンスーンの降雨は,15万5千年にわたる北部の気候変化を密接に追跡しています. この大気結合は,高緯度の不安定がモンスーンの動態に大きな影響を与えることを示しています.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- 気候変動のダイナミクス
- 海洋学 海洋学とは
背景:
- 過去の気候の再構築は,現在の気候変動を理解するために不可欠です.
- 西アフリカモンスーン (WAM) システムは,地域の水文学と農業にとって不可欠です.
- 高緯度の気候の振動は,世界の気候パターンに大きく影響を与えます.
研究 の 目的:
- 過去15万5千年の西アフリカのモンスーン水学を再構築する.
- WAMと北極の高緯度の気候振動の間の関連性を調査する.
- 海面温度や大気組成を含むWAM変動の要因を理解する.
主な方法:
- ギニア湾の海洋堆積物核から採取したプランクトンのフォラミニフェラにおけるBa/Ca比と酸素同位体組成の分析.
- Mg/Ca比を用いた海面温度 (SST) の再構築.
- WAMプロキシ,SST,北方高緯度気候記録 (スタジアムおよびインタースタジアム) の相関分析.
主要な成果:
- 東方赤道大西洋 (EEA) に流入する河川淡水の百年規模の変動は,北方高緯度の気候現象と同期しています.
- EEA SSTsは,主に温室効果ガスと太陽熱による北のミレニアムスケールの変動に対する分離反応を示しています.
- 強化されたモンスーン降雨の発生は,氷河期と氷河期間の移行の間に,EEA SSTの変化に最大7000年遅れがあります.
結論:
- 北部の高緯度の気候の不安定さは,西アフリカのモンスーンの動態に支配的なコントロールを行います.
- 大気連結は,北部のスタジアル・インタースタジアルサイクルと脱氷の出来事を,WAMの変動と結びつける.
- この発見は,高緯度の気候が低緯度のモンスーンシステムに及ぼす広範な影響を強調しています.
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