Abstract In this study, we examined the possible impacts of atmospheric model resolution and physics on simulating two types of El Nino events. Four experiments were conducted using two different versions of the Community Atmosphere Model (i.e., CAM4 and CAM5) at two different resolutions. Compared with the CAM4 experiments, the CAM5 experiments yielded longer periods for both types of El Nino events, while the period yielded by the CAM5 experiments with a higher resolution was closest to the observations; the CAM5 experiments also had a larger anomaly amplitude of the thermocline depth during Eastern-Pacific (EP) El Nino events. All four coupled experiments could accurately simulate the phase locking of the Central-Pacific (CP) El Nino events but not the peak phase of the EP El Nino events; specifically, in the two CAM4 experiments, the peak phase appeared too early compared with the observations. Interestingly, the coupled experiment with a lower resolution or CAM5 could yield much stronger El Nino and larger El Nino-Southern Oscillation (ENSO) skewness than the experiment with a higher resolution or CAM4. The amplitude in the CAM4 experiment with a higher resolution was the lowest but was closest to that observed. Heat budget analysis of each of the four coupled experiments demonstrated that the thermocline feedback in the coupled model was much larger than that observed for the EP El Nino events. There existed a large deviation in the simulated zonal advection terms; specifically, the zonal advection term of the anomalous temperature gradient found by averaging the mean current over the Nino4 region was unrealistically negative during the developing phase of the CP El Nino events and directly affected the simulation of the CP El Nino events in the coupled experiments with a lower resolution.

中文翻译：

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大气物理和模式分辨率在两种厄尔尼诺模拟中的作用

摘要 在这项研究中，我们研究了大气模式分辨率和物理学对模拟两种类型的厄尔尼诺事件可能产生的影响。使用两种不同版本的社区大气模型（即 CAM4 和 CAM5）以两种不同的分辨率进行了四次实验。与 CAM4 实验相比，CAM5 实验对两种类型的厄尔尼诺事件产生的周期更长，而分辨率更高的 CAM5 实验产生的周期与观测结果最接近；在东太平洋 (EP) 厄尔尼诺事件期间，CAM5 实验还具有较大的温跃层深度异常幅度。四个耦合实验都可以准确模拟中太平洋（CP）厄尔尼诺事件的锁相，但不能准确模拟EP厄尔尼诺事件的峰值相位；具体来说，在两个 CAM4 实验中，与观察结果相比，峰值相位出现得太早。有趣的是，与具有更高分辨率或 CAM4 的实验相比，具有较低分辨率或 CAM5 的耦合实验可以产生更强的厄尔尼诺现象和更大的厄尔尼诺-南方涛动 (ENSO) 偏度。具有更高分辨率的 CAM4 实验中的幅度最低，但最接近观察到的幅度。四个耦合实验中每一个的热预算分析表明，耦合模型中的温跃层反馈比在 EP 厄尔尼诺事件中观察到的要大得多。模拟的纬向平流项存在较大偏差；具体来说，