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Climate Modeling results show that about 50% of the Earth’s outgoing radiation and 75% of the atmospheric
outgoing radiation are contained in the far infrared. Generally the earth is considered as a 220~230 K blackbody, and the
peak breadth of the Earth’s outgoing radiation is around the wavelength of 10 micron. The atmospheric outgoing
radiation are contained with five spectral intervals: the water vapor band from 6.33 to 6.85 microns, the ozone band from
8.9 to 10.1microns, the atmospheric window from 10.75 to 11.75 microns, the carbon dioxide band from 14 to 16
microns, and finally the rotational water vapor band from 21 to 125 microns. The properties of the carbon dioxide band
is stable than other bands which has been chosen for the work Spectrum of the earth sensors. But the radiation energy of
carbon dioxide band is variety and it is a function of latitude, season and weather conditions. Usually the luminance of
the Earth’s radiation (14 to 16 μm) is from 3 to 7 W/m2Sr.
Earth sensor is an important instrument of the Attitude and Orbit Control System (AOCS), and it is sensitive to the curve
of the earth’s and atmospheric outgoing radiation profile to determine the roll and pitch angles of satellite which are
relative to nadir vector. Most earth sensors use profile data gathered form Project Scanner taken in August and December
1966.
The earth sensor referred in this paper is the conical scanning earth sensor which is mainly used in the LEO (Low Earth
Orbit) satellite. A method to determine the luminance of earth’s and atmospheric outgoing radiation (carbon dioxide)
using the earth sensor is discussed in this paper. When the conical scanning sensor scan form the space to the earth, a
pulse is produced and the pulse breadth is scale with the infrared radiation luminance. Then the infrared radiation
luminance can be calculated. A carbon dioxide radiance model of the earth’s and atmospheric outgoing radiation is
obtained according the luminance data about with different latitudes and seasons which are measured form the conical
scanning earth sensors of ZY-1 satellite.
When the carbon dioxide radiance model has been collected, it can be fed directly to the earth sensors to improve their
accuracy. It also can be supplied for the research of the content and distribution of carbon dioxide in the atmosphere.
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