The implementation of the international Array for Real-time Geostrophic Oceanography (Argo) Project facilitates unprecedented global ocean observations of sea-water temperature and salinity from the sea surface to a depth of 2000 m. Application of these new oceanic data in atmospheric and oceanic research and operation is essential for understanding the atmospheric and oceanic variability and increasing the accuracy of climate prediction and oceanic monitoring and analysis. The global ocean data assimilation systems are set up by developing a nonlinear temperature- salinity coordinated assimilation scheme and adjusting the temperature and salinity on the basis of altimetry data, which enhances the monitoring and analyzing capability for the global ocean. The global ocean data assimilation systems are integrated with coupled atmosphere-ocean models, which increases the forecast skills for short-term climate prediction. Argo data are applied for improving physical parameterization schemes in oceanic models, and the model capability of describing the real oceans and forecasting El Niño/Southern Oscillation is increased. A novel method has been developed for estimating surface and mid-layer ocean currents on the basis of the trajectories of Argo float drifting, which improves the accuracy of estimation of global surface and mid-layer ocean currents and makes up the insufficiency in observed ocean currents.