From: Asahi
Published January 7, 2009 08:31 AM

Tracking greenhouse gases from space

In a world first, Japan will attempt to monitor the Earth's "breathing" from space, via satellite, as part of efforts to better understand the greenhouse effect.

The Japan Aerospace Exploration Agency (JAXA)--working in conjunction with the Environment Ministry and the National Institute for Environmental Studies--will launch the Greenhouse Gases Observing Satellite (GOSAT) Ibuki using the H-2A rocket on Jan. 21.

The name of the satellite derives from the Japanese word for breathing.

The total project cost, including the launch, is estimated at 34.6 billion yen.

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The satellite will monitor emissions of carbon dioxide and methane, two of the six gases regulated under the Kyoto Protocol, which requires industrialized countries to drastically cut greenhouse gas emissions.

The two gases are said to be responsible for about 80 percent of the greenhouse effect.

Observation of the density of carbon dioxide on the ground started about 50 years ago.

According to the World Meteorological Organization's World Data Center for Greenhouse Gases, as of Nov. 27, there were 283 observation points across the world that monitored carbon dioxide and other greenhouse gases.

An orbiting satellite, however, will provide scientists with a perspective unavailable from terrestrial observatories.

"From space, we can observe the Earth almost in its entirety," said Takashi Hamazaki, GOSAT project manager at JAXA.

Tatsuya Yokota, who heads the satellite observation office of the National Institute for Environmental Studies, said: "In addition to the ocean, there are many places on land where there are no observation points, in such regions as Africa, the Middle East and South America."

Ibuki will monitor 56,000 locations on Earth from an altitude of 666 kilometers.

It will orbit the Earth in about 100 minutes and return to the same position in three days. During that time, Ibuki will observe sunlight reflected on the Earth's surface.

Carbon dioxide and methane in the atmosphere absorb infrared rays of specific wavelengths.

The denser the gases, the more light they absorb. Therefore, the density of the gases can be calculated from the measured strength of the light of those wavelengths.

Article Continues: http://www.asahi.com/english/Herald-asahi/TKY200901010068.html

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