Climate study has two aspects: basic understanding of physical mechanism and future climate projection. In the former study, how and why the equilibrium state with fluctuation and drastic regime shift do occur are investigated. On the other hand, the latter study focusses on the near-future climate assessment and directly contributes to the society by providing the reliable information. For proceeding the climate study, it is necessary to understand several important but basic feedbacks accompanying with greenhouse gases, e.g., carbon cycle feedback, ice-albedo feedback, cloud feedback, water vapor feedback, and so on. As an introduction, I will give explanation for such processes as simply as possible.
Although the climate study relies on the global/regional model, there exists several issues in climate modeling, numerical convergence at high resolution, cloud expression, turbulence theory, and so on. I will review our representative climate studies in the last several years: numerical convergence of deep convection and prediction skill of Madden Julian Oscillation, poleward transport of black carbon, and indirect effect of aerosol on cloud in the global model study, and numerical exploration of dust devil aspect in Mars and the development of a new assessment method of regional climate in the regional model study.
I also talk about the future direction of our research. As the modeling issue, the turbulence-cloud coupling scheme is a crucial issue. This would require reconstruction of turbulence theory including water vapor saturation. Scientifically, cloud organization and hierarchical structure are a key for understanding the climate equilibrium when such phenomena are regarded as the energy system.