Looking at a landscape through a fogged-up window, you can make out the general shapes, but the details are lost. The climate model ICM used to be such a window: its atmospheric grid had cells of 3.75 degrees, and many important processes smeared into a blur. In the new version, ICM.V2, the cells are half that size, 1.875 degrees. Now the model sees the climate picture of East Asia and the western North Pacific much more clearly.
El Niño is a warming of the equatorial Pacific that occurs every few years and affects weather worldwide. For East Asia, two mechanisms are especially important. First: after El Niño, the Indian Ocean retains heat for a long time, like a sun-warmed rock holding warmth after sunset, and this heat modifies summer rains. Second: in the western North Pacific, wind and ocean temperature anomalies reinforce each other, like two people swinging a swing in rhythm.
The previous model had errors: summer rains shifted northward, and El Niño anomalies stretched too far west. The new version fixed these issues, though a new one emerged: in summer, over the western North Pacific, the model paints cold where it is actually warm. Scientists are aware of this problem and will address it. The key point is that the lens is now focused, and climate details are much clearer.
The ICM.V2 model was integrated for 1000 model years, equivalent to a thousand-year climate history, yet it uses an atmospheric resolution of T63, which corresponds to a grid of about 210 km at the equator, enough to distinguish individual monsoon systems but still too coarse to reproduce mesoscale phenomena such as tropical cyclones.