Collaborative Research: Tropical Variability in a New Generation of Coupled Climate Simulations with Explicitly Resolved Convection

研究是在社区气候系统模式（CCSM，第3版）的超参数化（SP）版本或SP-CCSM进行的模拟上进行的。 在耦合气候模式中使用的大气成分模式通常使用对流参数化，其中对流的影响估计没有实际解决对流。在超级参数化中，参数化在模型水平网格中的每一点上都被云解析模型所取代。通过这种方式，气候模式获得了全球云分辨模式的一些好处，而无需在地球仪上运行这样一个高分辨率（7公里或更小）非静力模式的巨大计算费用。基于20年的初步模拟，SP-CCSM的热带模拟结果优于CCSM 3，包括改进了厄尔尼诺/南方涛动事件的周期性，减少了经典的双ITCZ偏差，以及更可信的Madden-Julian涛动（MJO）模拟。首先，利用SP-CCSM及其大气模式，分析了地面通量、海气相互作用和小尺度对流过程在MJO事件中的作用。 本研究还考虑了MJO影响亚洲夏季风的机制。 其次，这项工作旨在了解MJO对赤道太平洋厄尔尼诺/南方涛动事件的影响，这项工作通过其对MJO事件的预测潜力产生更广泛的影响，这些事件对亚洲夏季风和美国的天气产生影响。 研究结果还可能导致改进天气和气候模式中热带对流的参数化。 此外，该项目还支持一名博士后研究人员，从而为该领域的下一代科学家提供支持。

Research is conducted on simulations performed with the superparameterized (SP) version of the Community Climate System Model (CCSM, version 3), or SP-CCSM. The atmospheric component model used in a coupled climate model typically uses a parameterization for convection, in which the effects of convection are estimated without actually resolving the convection. In superparameterization, the parameterization is replaced by a cloud resolving model at each point in the model's horizontal grid. In this way the climate model gains some of the benefits of a global cloud resolving model without the enormous computational expense of running such a high-resolution (7km or less) nonhydrostatic model over the globe. Based on a 20-year simulation performed as preliminary work, SP-CCSM produces a better tropical simulation than CCSM3, including improvements in the periodicity of El Nino/Southern Oscillation events, reduction in the classical double-ITCZ bias, and a more credible simulation of the Madden-Julian Oscillation (MJO).Two research objectives are addressed in this research: first, SP-CCSM and its component atmospheric model are used to evaluate the roles of surface fluxes, air-sea interactions, and small-scale convective processes in producing MJO events. This research also considers the mechanisms through which the MJO affects the Asian summer monsoon. Second, the work seeks to understand the effect of the MJO on El Nino/Southern Oscillation events in the equatorial Pacific.The work has broader impacts through its potential to forecasts of MJO events, which have consequences for the Asian summer monsoon and weather in the United States. Research results may also lead to improvements in the parameterization of tropical convection in weather and climate models. In addition, the project supports a postdoctoral researcher, thereby providing for the next generation of scientists in this field.