Regional moisture change over India during the past Millennium: A comparison of multi-proxy reconstructions and climate model simulations
Regional moisture change over India during the past Millennium: A comparison of multi-proxy reconstructions and climate model simulations
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DOI：
10.1016/j.gloplacha.2014.08.016
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发表时间：
2014-11
影响因子：
3.9
通讯作者：
Stefan Polanski;B. Fallah;D. Befort;Sushma Prasad;U. Cubasch
中科院分区：
文献类型：
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作者：
Stefan Polanski;B. Fallah;D. Befort;Sushma Prasad;U. Cubasch
用ECHAM5模式模拟了近千年来印度季风在两个不同时间段的变化：中世纪气候异常和小冰期。这些模拟与新的百年分辨率古重建进行了比较，这些古重建是从喜马拉雅和印度中部两个核心区的各种定年的多个代理推断出来的。重建的小冰期和中世纪气候异常之间的古水文变化描绘了喜马拉雅和印度中部之间的偶极子模式，这也被模式所捕捉。在中世纪气候异常中，模式在夏季(冬季)表现出比小冰期更强(更弱)的偶极子信号。在“中世纪气候异常减去小冰期”的夏季(冬季)月份，该模式模拟了喜马拉雅东部(西部和中部)更潮湿的条件。在印度中部，气候变暖期间印度夏季风减弱的模拟结果与洛纳尔湖记录中重建的干燥信号相吻合。在模式模拟的基础上，我们可以区分出导致水汽异常的三种物理机制：(I)喜马拉雅西部和中部在冬季受到热带西风的影响；(Ii)喜马拉雅东部受到孟加拉湾和印度次大陆之间温度梯度夏季变化的影响，以及25°N以北加强的印度-东亚季风联系纬向带的影响，(3)印度中部以阿拉伯海北部夏季海温异常为主，这种异常对湿气团的大范围平流有影响。阿拉伯海的温度与调节印度季风强度的印度-太平洋暖池有关。
The Indian Monsoon Variability during the past Millennium has been simulated with the ECHAM5 model in two different time slices: Medieval Climate Anomaly and the Little Ice Age. The simulations are compared with new centennial-resolving paleo-reconstructions inferred from various well-dated multi-proxies from two core regions, the Himalaya and Central India. A qualitative moisture index is derived from the proxies and compared with simulated moisture anomalies.The reconstructed paleo-hydrological changes between the Little Ice Age and the Medieval Climate Anomaly depict a dipole pattern between Himalaya and Central India, which is also captured by the model.In the Medieval Climate Anomaly the model exhibits stronger (weaker) dipole signals during summer (winter) compared to Little Ice Age. In summer (winter) months of “Medieval Climate Anomaly minus Little Ice Age” the model simulates wetter conditions over eastern (western and central) Himalaya. Over Central India, a simulated weakening of Indian Summer Monsoon during warmer climate is coincident with reconstructed drying signal in the Lonar Lake record.Based on the model simulations, we can differentiate three physical mechanisms which can lead to the moisture anomalies: (i) the western and central Himalaya are influenced by extra-tropical Westerlies during winter, (ii) the eastern Himalaya is affected by summer variations of temperature gradient between Bay of Bengal and Indian subcontinent and by a zonal band of intensified Indian–East Asian monsoon link north of 25°N, and (iii) Central India is dominated by summer sea surface temperature anomalies in the northern Arabian Sea which have an effect on the large-scale advection of moist air masses. The temperatures in the Arabian Sea are linked to the Indo Pacific Warm Pool, which modulates the Indian monsoon strength.