风云二号卫星地球观域修正算法
Adjusting Methods of Earth Observation Field of FY-2 Meteorological Satellite
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摘要: 风云二号静止气象卫星在获取图像时, 必须使扫描辐射计的观域对准地球。卫星在轨道上受到各种摄动力的作用, 使轨道和姿态改变, 扫描辐射计的地球观域随之发生变化。卫星扫描辐射计对地球观域的偏差会影响图像定位的精度, 因此对准观域的工作是日常业务工作的一部分, 不仅在卫星定点之初启动观测时, 而且在业务运行的过程中, 都需要通过地面遥控指令进行修正。该文提出了一种风云二号静止气象卫星扫描辐射计地球观域修正量和调整方向的算法, 以替代人工目测卫星原始云图进行的卫星观域调整控制决策。这种算法的实施可以提高风云二号气象卫星云图获取作业的可靠性。Abstract: 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.
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表 1 卫星定点于105°E时β角修正脉冲量的执行个数①②③
Table 1 Executed number of β angle compensation pulse quantum(locating 105°E only)
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