The Global Change Observation Mission (GCOM) aims to construct, use, and verify systems that enable continuous global-scale observations (for 10 to 15 years) of effective geophysical parameters for elucidating global climate change and water circulation mechanisms. The GCOM mission is a two series of satellites, GCOM-W for observing water circulation changes and GCOM-C for climate changes. The GCOM-W with a microwave radiometer onboard will observe precipitation, vapor amounts, wind velocity above the ocean, sea water temperature, water levels on land areas, and snow depths.