Abstract:The ocean is one important component of the Earth system. There exist various processes in the ocean which can have significant influences on the climate and environment on the Earth, including the El Niño-Southern Oscillation (ENSO) and tropical instability waves (TIWs). These phenomena and signals result from complicated interactions among oceanic processes on multiple scales and among multispheres (such as the atmosphere, hydrosphere, biosphere and so on). Because the ocean exhibits such great diversity and variability on various space-time scales, the ocean should be studied as a system, taking into account interactions and taking different approaches in a coherent way (observation, theories, simulation and prediction etc.). Based on process understanding, models need to be developed as a powerful tool for simulation, prediction and projection. As the strongest interannual signal on the Earth, ENSO exerts significant influences on weather and climate worldwide. Examples are given for the modulating effects on ENSO by feedback processes on multiple time scales and multi-spheres, including ocean biology-induced heating and TIWs.