GCOM (Global Change Observing Mission) satellites are Japanese Earth resources satellites to improve the accuracy of global observations begun by ADEOS and collect data on worldwide environmental change.

 

GCOM-W (Global Change Observation Mission – Water "Shizuku") was the first in the GCOM series. Its mission was to observe the water cycle. The satellite carried the AMSR2 (Advanced Microwave Scanning Radiometer 2) instrument, successor to the AMSR-E carried by Aqua. This microwave radiometer observed precipitation, water vapor, wind velocity above the ocean, sea water temperature, water levels on land areas, and snow depths. GCOM-W was launched on 17 May 2012, by an H-IIA rocket, and flew in a sun-synchronous, polar orbit (altitude 700 kilometers) as part of the "A-train" satellite constellation. It successfully began collecting data on 4 July 2012.

 

GCOM-C1 (Global Change Observation Mission – Climate "Shikisai") was the first satellite in the GCOM-C series. It monitors global climate change by observing the surface and atmosphere of Earth. Through use of its SGLI (Second generation GLobal Imager) optical instrument, it collected data related to the carbon cycle and radiation budget, including measurements of clouds, aerosols, ocean color, vegetation, and snow and ice. From its sun-synchronous orbit (altitude 798 kilometers), SGLI collected a complete picture of Earth every 2–3 days with a resolution of 250–1000 meters, across the UV, visible, and infrared spectra. GCOM-C was launched on 23 December 2017 by an H-IIA rocket.