Two‐Dimensional Idealized Hadley Circulation Simulation for Global High Resolution Model Development.

A new framework for the development of global high resolution models using a vertical‐meridional, two‐dimensional pole‐to‐pole domain is proposed. Compared with the three‐dimensional global model, the two‐dimensional framework can simulate cloud‐scale convection at significantly reduced computational cost, data volume, and turn‐around time, and accelerate the development phase. Although idealized, it allows for simulation of various clouds and scale interactions under a wide range of environmental conditions, even though zonal waves such as mid latitude storms cannot be simulated. Physics schemes can be tested and assessed over a full array of simultaneously occurring cloud regimes. The framework can serve as an intermediate step between a one‐dimensional simulation and a full three‐dimensional global model. Using this framework, we analyze the resolution dependencies of simulated clouds and the Hadley circulation in a range of global high resolution models by performing multiple 1000‐day simulations; for some resolutions tested, for example, 2 km horizontal resolution, three‐dimensional simulation is not feasible at the present time. Analysis shows that both horizontal and vertical resolution determine the properties of the Hadley circulation and clouds, and that the differences among the simulated Hadley circulations are understood as differences in scale interactions influenced by resolution. Plain Language Summary: The resolution of global climate models has increased dramatically in recent years. While an increase in resolution usually provides improvements in the numerical solution, it imposes an enormous increase in computational cost. This becomes more serious in the model development phase because numerous tests are required to assess the performance, ideally in a similar computational domain and resolution as the target simulations. We approach the problem by applying a vertical‐meridional, two‐dimensional framework with a computational domain that extends from the south‐pole to the north‐pole and includes the entire troposphere. By removing the zonal extension, we can significantly reduce computation time, and easily increase model resolution and the number of test cases. This simplified framework is capable of representing the Hadley circulation, which is a fundamental feature of Earth's atmosphere, and allows us to study internal feedbacks in the Hadley circulation as well as effects of model configurations on the simulated atmosphere. Key Points: New framework simulates clouds and Hadley circulation in a vertical‐meridional, two‐dimensional domainUsefulness of the framework is presented by a resolution sensitivity study with multiple 1000‐day simulationsScale interactions differ between high and low resolution resulting in single or split Hadley circulations [ABSTRACT FROM AUTHOR]

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