When was the first satellite altimetry map of the oceans produced?

Global ocean-height mapping entered a new era after the Topex/Poseidon satellite launched in 1992. By measuring tiny changes in sea-surface height, scientists could map currents, eddies, and features of the ocean floor that subtly affect sea level. The first detailed global maps based on these observations appeared in the early 1990s. These maps helped reveal patterns such as the shape of major currents and even previously hidden seafloor structures. Satellite altimetry remains a core tool in modern oceanography.