| SU Tonghua,XUE Feng,SUN Hongchuan,ZHOU Guangqing. 2015. The El Niño-Southern Oscillation cycle simulated by the climate system model of Chinese Academy of Sciences. Acta Oceanologica Sinica, 34(1):55－65 |
| The El Niño-Southern Oscillation cycle simulated by the climate system model of Chinese Academy of Sciences |
| 中国科学院气候系统模式模拟的ENSO循环 |
| Received:April 07, 2014 Revised:September 10, 2014 |
| DOI：10.1007/s13131-015-0596-9 |
| Key words:climate system model of Chinese Academy of Sciences El Niño-Southern Oscillation cycle El Niño thermocline wind stress |
| 中文关键词: 中国科学院气候系统模式 ENSO循环 El Niño 温跃层 风应力 |
| 基金项目:The Strategic Priority Research Program of Chinese Academy of Sciences under contract No. XdA05110201; the National Basic Research Program (973 Program) of China under contract No. 2010CB951901. |
| Author Name | Affiliation | E-mail | | SU Tonghua | International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Fujian Meteorological Observatory, Fuzhou 350001, China | | | XUE Feng | International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | fxue@lasg.iap.ac.cn | | SUN Hongchuan | Jiangsu Meteorological Observatory, Nanjing 210009, China | | | ZHOU Guangqing | International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | |
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| Abstract: |
| On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences (CAS-ESM-C) in simulating the El Niño-Southern Oscillation (ENSO) cycle is evaluated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature (SST) in the tropical Pacific, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the El Niño onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster development of an El Niño. during the decay stage, owing to a stronger El Niño in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an El Niño decays into a La Niña through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attributed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean. |
| 中文摘要: |
| 基于中国科学院气候系统模式200年的模拟结果, 评估了该模式对ENSO循环的模拟能力, 包括ENSO的发生、发展和衰减过程. 结果表明, 模式能模拟出热带太平洋海表温度的季节和年际变化以及ENSO的季节锁相. 此外, 模式还抓住了El Niño爆发的两个先决条件, 即赤道西太平洋的西风异常和偏暖的海表温度. 由于外热带经向风强迫偏强, 模式中西风异常偏强, 加之模式中温跃层偏浅、倾斜程度偏弱, 西太平洋暖海表温度异常东传速度偏快, 导致El Niño发展偏快. 在衰减阶段, 由于模式中El Niño偏强, 热带大气对东太平洋变暖的二次Gill型响应也偏强, 导致西太平洋出现持续的东风异常. 与此同时, Ekman抽吸抬升了西太平洋的温跃层, 暖池出现冷异常, 二者共同作用导致了El Niño衰减为La Niña. 模式中ENSO周期偏短、振幅偏大, 这与赤道太平洋温跃层偏浅有关, 温跃层偏浅将导致上层海洋中热量的再分配加速完成. |
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