Global Sea-Level Observing System. A component of the Global Ocean Observing System (GOOS). The IOC of UNESCO established GLOSS in 1985 originally to improve the quality of sea level data as input to studies of long-term sea level change. It consists of a core network of approximately 300 stations distributed along continental coastlines and throughout each of the world’s island groups. The GLOSS network also supports sea level monitoring for tsunami warning with minimum operational standards of 15-minute data transmissions of one-minute sampled data.