1/4° global temperature and salinity objective analysis using 4D-MGA

A global, weekly T & S gridded dataset with a horizontal resolution of 1/4° and a depth range of 0–1500 m from 2005 to 2023 is reconstructed using a four-dimensional multigrid analysis (4D-MGA) framework. With minimal prior statistical assumptions, the 4D-MGA efficiently extracts information from in-situ T & S profiles and satellite-observed sea level anomalies by integrating multiscale spatiotemporal correlation and physical constraints. The validations show that the 4D-MGA product successfully delivers a credible, high-resolution analysis that combines robustness with reliable mesoscale information. The dynamic height anomaly and geostrophic current derived from our product show high consistency with satellite observations and previous studies. Furthermore, the clear recirculation in the western boundary currents (WBCs) can be well captured by the 4D-MGA product. The product is then applied to investigate the linear trends of geostrophic transport within five key sections in WBCs. The 4D-MGA product is a subset of the high-resolution, objective analysis, gridded dataset for oceans, and it has the potential to advance our understanding of ocean dynamics and climate change.