GCOM-W (Shizuku)

GCOM-W [JAXA]

The GCOM-W (Global Change Observation Mission - Water) or Shizuku satellite 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. Water circulation changes will be observed by a microwave radiometer onboard the GCOM-W (Water) satellite (scheduled to be launched in Japan Fiscal Year 2011). The GCOM-W will observe precipitation, vapor amounts, wind velocity above the ocean, sea water temperatures, water levels on land areas and snow depths. Climate change observation will be performed by a multi-wavelength optical radiometer onboard the GCOM-C (Climate) satellite (under consideration) on clouds, aerosol, seawater color (marine organisms), vegetation, snow and ice. These satellites will enable us to perform comprehensive observations of the surface layer of the Earth such as the atmosphere, including clouds, land, oceans and the cryosphere.

The Advanced Microwave Scanning Radiometer 2 (AMSR2) is a sensor to observe radiometers, or microwaves emitted naturally from the ground, sea surface and atmosphere, using 6 different frequency bands ranging from 7 GHz to 89 GHz. The strength of a natural microwave is determined by its characteristics and moisture, including the surface condition and temperature of the material. Although it depends on the frequency, the microwave is very weak. AMSR2 will detect such weak microwaves at an altitude of 700 kilometers and measure the strength of them with a very high accuracy. For example, by measuring the strength of a microwave emitted from the sea surface with the AMSR2, one can understand the water temperature of the sea surface to an accuracy of 0.5 degrees Celsius. The antenna of the AMSR2, which receives microwaves from the ground, arc scans the ground surface at a ratio of one turn every 1.5 seconds and observes an area approximately 1,450 kilometers wide in one scan. Using this scanning method, the AMSR2 can observe over 99 percent of the Earth's area in just 2 days. The diameter of the antenna is about 2 meters, making it the world's largest observation sensor aboard a satellite. The height of the rotating part is about 2.7 meters and the weight is about 250 kilograms. The AMSR2 can keep rotating such a large and heavy antenna at a speed of one turn per 1.5 seconds for 24 hours a day and more than five years without a minute of rest.

GCOM-W is also equipped with the Automatic Identification System for ships (AIS) receiver so that the satellite will also monitor oceans by receiving AIS signals from vessels. The SPace based AIS Experiment (SPAISE1) is a high performance satellite AIS. SPAISE1 development is JAXA's ongoing project in cooperation with NEC Corporation.