Asian summer monsoon precipitation recorded by stalagmite oxygen isotopic composition in the western Loess Plateau during AD1875-2003 and its linkage with ocean-atmosphere system
Asian summer monsoon precipitation recorded by stalagmite oxygen isotopic composition in the western Loess Plateau during AD1875-2003 and its linkage with ocean-atmosphere system
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DOI：
10.1007/s11434-008-0286-5
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发表时间：
2008-07-01
影响因子：
--
通讯作者：
Kathleen R. Johnson
中科院分区：
文献类型：
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作者：
Liu JingHua;Zhang PingZhong;Kathleen R. Johnson
利用甘肃武都万向洞石笋顶部16 mm的5个高精度Th-230测年数据和103个稳定氧同位素（δ O-18），重建了近100年来现代亚洲季风（AM）边缘带的季风降水变化。通过对近50 a来乌都地区实测降水资料的对比分析，发现两者具有较高的相似度，表明在降水的“量效应”控制下，乌都地区的AM强度和相关降水具有较好的代用性。近100年季风降水的变化可划分为3个阶段，即1875 ~ 1900年降水增加，1901 ~ 1946年降水减少，此后再增加。这种变化与中国历史文献记载的旱涝指数非常相似。在公元1875年至1977年期间，该洞穴的AM记录与太平洋年代际涛动（PDO）密切相关，在年代际尺度上，PDO的冷期对应较高的季风降水，反之亦然。AD 1977年后季风降水变化与PDO不一致，可能是发生在AD 1976/77年前后的北太平洋年代际气候跳变所致。这些结果表明，通过海洋/大气相互作用，AM和相关降水与太平洋之间存在很强的联系。这种关系将有助于预测AM季风区未来的水文循环，并提高利用洞穴观测资料的气候模式的预报潜力。
Based on 5 high-precision Th-230 dates and 103 stable oxygen isotope ratios (delta O-18) obtained from the top 16 mm of a stalagmite collected from Wanxiang Cave, Wudu, Gansu, variation of monsoonal precipitation in the modern Asian Monsoon (AM) marginal zone over the past 100 years was reconstructed. Comparison of the speleothem delta O-18 record with instrumental precipitation data at Wudu in the past 50 years indicates a high parallelism between the two curves, suggesting that the speleothem delta O-18 is a good proxy for the AM strength and associated precipitation, controlled by "amount effect" of the precipitation. Variation of the monsoonal precipitation during the past 100 years can be divided into three stages, increasing from AD 1875 to 1900, then decreasing from AD 1901 to 1946, and increasing again thereafter. This variation is quite similar to that of the Drought/Flooding index archived from Chinese historical documents. This speleothem-derived AM record shows a close association with the Pacific Decadal Oscillation (PDO) between AD 1875 and 1977, with higher monsoonal precipitation corresponding to cold PDO phase and vice versa at decadal timescale. The monsoonal precipitation variation is out of phase with the PDO after AD 1977, probably resulting from the decadal climate jump in the north Pacific occurring at around AD 1976/77. These results demonstrate a strong linkage between the AM and associated precipitation and the Pacific Ocean via ocean/atmosphere interaction. This relationship will aid to forecast future hydrological cycle for the AM monsoon region, and to improve forecasting potential of climatic model with observation data from cave.