Adjusting Methods of Earth Observation Field of FY-2 Meteorological Satellite

As the most significant achievement of remote sensing detection for Earth surface and atmosphere, China'scapability of weather forecast, prevention from various kinds of weather disasters as well as environment protection is improved by geostationary meteorological satellites.FY-2 series is the first generation of Chinese geostationary meteorological satellites.It can be used for continuous real-time observation on the variation of weather over China and its surrounding area, and an importantrole is also played in accurate medium-and long-term weather forecast.FY-2D satellite is launched successfully in Dec 2006, and two geostationary meteorological satellites locatingwest and east over China are realized, their image dissemination coverage are very wide.The composite observation is not only extremely significant to China's weather forecast, hazard reduction, global climate change observation, but also meteorological service is provided to East Asia, South Asia and even Australia and part ofAfrica.China becomes one of the most important countries of meteorological satellite in the world.Geostationary satellite is only relatively still to the Earth.When FY-2 geostationary meteorological satelliteis located to operational position, observation area must be adjusted before their original image acquisition in order to target at Earth medially.Due to the action of Earth's rotation and other impetuses, the actual satellite orbit and attitude vary continuously, the raw images received may have shifts between east and west.The precision of framing could be influenced by the warp of scan radiometer of FY-2 meteorological satellites for the Earthobservation field.Therefore, once the Earth drifts away from the center of the satellite observation field, adjusting should be taken in order to control the scan radiometer aiming at the Earth.Therefore, it is part of the dailytask not only in the satellite original image acquisition period, but also frequently in its whole operational lifetime.Adjusting of observation field is done by sending several data-injected telecommands to the satellite fromthe ground station.A kind of self-correcting arithmetic is proposed by which the adjusting numbers and orientation for controlling scan radiometer can be calculated.That is to say that a result of the arithmetic can be used to choose data-injected telecommands and its pulse number instead of man-made decision.The data of arithmetic could be acquired by using the value of N, which comes from Synchronizer Data Buffer within CDAS(Commands and DataAcquisition Station)or using simulated telemetry data of FY-2 satellite.It is one of the software programs inSatellite Control Center correctly used for FY-2A and FY-2B when they are in normal operational mode and during their eclipse.It will be adopted to double satellites operational system to reduce satellite controlling manmade mistakes, to ensure security of satellites, to enhance its automatic operational abilities, and to increase thereliability of image obtained task of FY-2 meteorological satellite.