State of the tropical Pacific Ocean and its enhanced impact on precipitation over East Asia during marine isotopic stage 13
State of the tropical Pacific Ocean and its enhanced impact on precipitation over East Asia during marine isotopic stage 13
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DOI：
10.1007/s00382-014-2227-0
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发表时间：
2015-02
期刊：
影响因子：
4.6
通讯作者：
M. Karami;M. Karami;N. Herold;N. Herold;A. Berger;Q. Yin;H. Muri;H. Muri
中科院分区：
文献类型：
--
作者：
M. Karami;M. Karami;N. Herold;N. Herold;A. Berger;Q. Yin;H. Muri;H. Muri
多个陆地记录表明，大约50万年前的间冰期海洋同位素第13阶段（MIS-13）是近100万年来东亚夏季风（EASM）最强的时期。这是出乎意料的，因为与其他间冰期相比，MIS-13在全球范围内更冷，二氧化碳浓度更低。利用Hadley中心耦合模式第3版（HadCM3）和社区气候系统模式第3.0版（CCSM3）两个大气-海洋环流耦合模式，模拟了相对于工业化前（PrI）情况下不同日照和温室气体浓度强迫下的MIS-13气候。两种模式都证实了mis13期间的EASM比PrI更强。本文重点分析了热带太平洋对EASM的影响。我们的模拟表明，在MIS-13期间，热带太平洋的平均气候状态为La Niña-like，与热带外区相关的远相关有利于东亚地区降水增加。与PrI相比，夏季（6 - 7 - 8月）海温（SST）在热带太平洋东部偏暖，在西部偏冷。与之前的研究一致，我们发现在MIS-13期间，热带太平洋中部夏季较冷的海温促进了热带太平洋与东亚东部的高层遥相关。它还有助于北太平洋副热带高压的加强，从而将更多的水汽输送到东亚。我们认为，夏季热带太平洋东西海温差的减小有助于维持热带太平洋与东亚的遥相关。在我们的MIS-13模拟中，热带太平洋海温与东亚热的相关性更高，进一步支持了它们之间关系的增强。发现El Niño南方涛动对东亚地区降水的纯粹影响在MIS-13中对HadCM3增加了30%，而对CCSM3的影响较小。更好地控制间冰期热带太平洋海温的时空变异性，有助于解释地质记录中观测到的miss -13期间异常强的东亚热现象。
Multiple terrestrial records suggest that marine isotopic stage 13 (MIS-13), an interglacial period approximately 0.5 million years ago, had the strongest East Asian summer monsoon (EASM) of the last one million years. This is unexpected given that, compared to other interglacials, MIS-13 was globally cooler with a lower CO2concentration. We use two coupled atmosphere–ocean general circulation models, the Hadley Centre Coupled Model, version 3 (HadCM3) and Community Climate System Model, version 3.0 (CCSM3), to simulate the climate of MIS-13 forced with different insolation and greenhouse gas concentrations relative to the pre-industrial (PrI) situation. Both models confirm a stronger EASM during MIS-13 compared to PrI. Here we specially focus on analyzing the impact of the tropical Pacific Ocean on the EASM. Our simulations suggest that the mean climatic state in the tropical Pacific during MIS-13 was La Niña-like and that associated teleconnections with the extra-tropics favored increased precipitation over the EASM. As compared to PrI, it is found that the summer (June–July–August) sea surface temperature (SST) is warmer in the eastern tropical Pacific Ocean and colder to the west. In concert with previous studies, we show that colder summer SSTs in the central tropical Pacific during MIS-13 promotes an upper-level teleconnection between the tropical Pacific Ocean and EASM. It also contributes to the strengthening of the northern Pacific subtropical high and, therefore, the transport of more moisture into the EASM. We suggest that the reduced east–west SST difference in the tropical Pacific in summer helps to maintain the teleconnection between the tropical Pacific and EASM. The correlation between tropical Pacific SSTs and the EASM was higher in our MIS-13 simulations, further supporting the enhancement of their relationship. It is found that the pure impact of El Niño Southern Oscillation on EASM precipitation increases by up to 30 % in MIS-13 for HadCM3 while it is minor for CCSM3. Better constraining the spatio-temporal variability of tropical Pacific SST during the interglacials may thus help explain the anomalously strong EASM during MIS-13 which has been observed from geological records.