基于地基观测的时序卫星红外光谱建模与分析

针对地基观测的卫星红外光谱受复杂因素的影响和外场试验对测量卫星物性信息的缺乏,无法解释卫星红外光谱反演出特征的有效性和具体物理意义的问题,提出了一种基于地基观测的卫星热红外光谱的建模和分析的方法.首先,考虑了太阳辐射、地球辐射、卫星各面对探测器的可见情况、地基探测器可探测卫星的范围、大气衰减等因素的影响,更加准确地建立卫星热红外光谱模型.然后,以风云三号卫星为例,利用该模型计算了在观测时序上卫星在地基探测器入瞳上的3—14μm红外光谱辐照度;分析了影响卫星红外光谱变化的主要因素.最后,利用普朗克函数拟合卫星红外光谱,提取出特征与卫星的物性比较,并对其进行分析.结果表明:在各种影响因素中,由卫星运动引起的对探测器可见情况的改变是影响卫星红外光谱数据的主要因素.等效温度和等效面积物理含义能被有效地解释,等效温度接近于太阳帆板的温度,温差仅在15 K左右,等效面积能表征卫星投影面积的变化;发现利用帆板和本体有较大的温差,能实现帆板和本体的分离,并实现新特征的提取.

Modeling and analyzing of time-resolved satellite infrared spectrum based on ground-based detector

Satellite infrared spectra based on ground-based detector are affected by complex factors such as satellite surface temperature, solar radiation, observation angle, etc, whose change cannot be detected in external field experiment. Therefore, it is impossible to analyze what are the main factors that affect the satellite infrared spectra. At the same time, due to the lack of physical information about the satellites through the external field experiment, the validity and physical significance of retrieving features from satellite infrared spectrum cannot be explained. In view of the above problem, a method to model and analyze satellite thermal infrared spectra based on ground-based detector is proposed. It is a feasible research method to accurately establish satellite thermal infrared spectrum model based on the ground detection, then to analyze the simulated infrared spectrum data. Firstly, considering the solar radiation, earth radiation, detectable range of the satellite on the detector, observation angle, atmospheric attenuation, etc., the satellite thermal infrared spectrum model can be established more accurately. Then, taking FY-3 satellite for example, the physical and orbital parameters of the satellite are set up, and the 3-14μm infrared irradiance of the satellite on the pupil of the detector is calculated by using the model. Meanwhile, the main factors affecting the infrared spectrum of the satellite are analyzed. Finally, the equivalent temperature and equivalent area are extracted by fitting the satellite infrared spectrum with the Planck formula. And they are compared with the physical properties of the satellite. The results show that among the various factors, with the satellite' movement, the change of the visible state of the satellite induced by the satellite's movement is the main factor that affects the satellite infrared spectrum. The physical meanings of the equivalent temperature and equivalent area can also be explained effectively. The equivalent temperature is close to the temperatures of the solar panels, and their temperature difference is only about 15 K. The change of equivalent area is consistent with that of the satellite projected area. Moreover, it is also found that there is a large temperature difference between the solar panels and the body, which makes their infrared spectra obviously different. Therefore, it is hopeful to obtain the areas and temperatures of the solar panels and the body respectively. This research can make up for the shortcomings of the external field experiments and promote the monitoring and recognizing of satellites by ground-based infrared detectors.