9．6～6．0kaB．P．阿曼降水重建及其与中国南方降水的对比

RAINFALL RECONSTRUCTION FROM OMAN DURING 9. 6- 6. 0ka B.P. AND ITS COMPARISON WITH THAT FROM SOUTHWEST CHINA

了解东亚季风和印度季风及其变化特征并认识它们的活动规律，有利于提高预报季风变化及区域降水的准确性。虽然最近几十年两个季风区提取的高分辨率古气候记录较多，但气候意义明确且可进行比较的记录尚不多见，限制了印度季风和东亚季风的对比及其动力学机制的探究。本文利用分别来自阿曼南部、北部的两个具有精确年代的石笋氧同位素记录，高分辨率重建了全新世早一中期印度季风区阿曼的降水序列，比较了同期印度季风降水与东亚季风降水的差异。研究结果表明，9．6～6．0kaB．P．期间阿曼降水总体上呈波动增加的趋势，与东亚季风区的中国南方降水变化基本同调。早一中全新世的弱厄尔尼诺一南方涛动（ENSO）可能是印度季风和东亚季风变化保持一致的原因。因为ENSO对两个季风系统的影响不同，强ENSO时可导致两者间的差异；弱ENSO时，则因其对两个季风系统的影响较小，使得两者间的差异并不明显。太阳变化驱动的ITCZ南北移动应是阿曼和中国南方降水同步变化的主要原因。

Understanding the variations of Indian monsoon and East Asian monsoon could improve the prediction accuracy of monsoon and regional rainfall. Unfortunately, among those high resolution paleoclimatic records from the two monsoon areas, few of them could provide comparable records with clear climate information, which makes it difficult to compare the two monsoon systems and to understand the difference of their driving forces. In this study, a high resolution rainfall sequence has been established during the Early-Middle Holocene by two stalagmite oxygen isotope records with precise chronology from the south and the north of Oman respectively and the Indian monsoon rainfall was compared with the East Asian monsoon rainfall at the same period. Reconstructed rainfall is robust to the uncertainty from the speleothem chronology and from the 6t80 records in various stalagmites from the same cave. It could be revealed that the rainfall in Oman is generally increasing with fluctuations during 9.6 N 6.0ka B.P. The rainfall increased during 9.6~8.5ka B.P., 8.0~7.6ka B.P., 7.3-6.9ka B.P. and 6.6-6.2ka B.P., while rainfall reduced during 8.5-8.0ka B.P., 7.6-7.3ka B.P., 6.9-6.6ka B.P. and 6.2-6.0ka B.P. The results suggest that the rainfall in Oman coincide with the the rainfall from Southwest China during the same period. Weak ENSO during the Early-Middle Holocene might be one of the reasons causing their similarity as the impacts of ENSO on the two monsoon systems are different. Strong ENSO influence could result in different between the two systems, and weak ENSO with less influence might lead to less difference between them. Therefore, ITCZ moving driven by insolution should be the main reason leading to the rainfall variation synchronously in both Oman and Southwest China.