西风爆发在CMIP5 中的模拟评价

赤道西风爆发现象(西风爆发)是指赤道表面西风突然增大的现象,已有研究表明赤道太平洋西风爆发与ENSO (El Niño-Southern Oscillation) 有密切的关系。本文就西风爆发现象在CMIP5中的模拟情况进行了相关评价,并将其与观测结果进行对比;同时对西风爆发与ENSO的关系、西风爆发与MJO的关系进行了细致的分析与评价。研究结果表明,模式可以很好地再现西风爆发随厄尔尼诺事件发生而向东移动的现象,这主要是由于赤道太平洋西风爆发与赤道太平洋海表温度有很好的对应关系。在大部分模式中,西风爆发领先于厄尔尼诺的发生,并对厄尔尼诺的发展有着相应的影响。与前人的研究结果不同,利用蒙特卡洛验证法证明MJO不能显著地增加西风爆发发生的概率,这一点也在大部分CMIP5模式中有所体现。

The evaluation of Westerly Wind Bursts in CMIP5 models

Equatorial Westerly Wind Bursts (WWBs) are characterized by sudden increase of surface westerlies over the equatorial region. Previous studies showed that the WWBs play a fundamental role in triggering and maintaining the El Niño event. In this thesis, we evaluate the simulation of WWBs in the state-of-the-art models from the Coupled Model Intercomparison Project phase5(CMIP5). Most of the models can reproduce the eastward propagation of WWBs in El Niño years, as occurrences of WWBs are strongly dependent on sea surface temperature in the tropical western-central Pacific. The WWBs generally occurs before the development of El Niño. Unlike what was proposed in previous studies, we found that MJO does not significantly increase the likelihood of WWBs in both observations and model simulations.