风云卫星大气掩星探测仪北斗观测数据处理的关键技术研究

Global Navigation Satellite System occultation sounder (GNOS) on board the FengYun 3C (FY3-C) satellite is the first BeiDou System (BDS)/GPS compatible RO sounder in the world, which uses an ultra stable crystal oscillator, so it is possible to calculate excess phase using zero differencing. In order to enhance the quality of the BDS RO product, and investigate the accurate consistence between BDS and GPS RO data, four main tasks will be conducted in this study. To simulate and analyze the distribution of the BDS RO events due to three different orbit types; to conquer the joint GPS/BDS LEO POD technique, then compare the error characteristics of the GPS, BDS and GPS/BDS POD results; to develop a excess phase calculation algorithm by single/zero differencing, then complete the analysis of its advantage; at last to analyze the effects of different LEO POD accuracies due to different orbit types, and GEO/IGSO satellite POD accuracies on the RO products' error characteristics. Since the BDS RO data that will be used in this study was obtained for the first time all over the world, therefore the BDS RO data processing algorithms investigation will be pioneering study. The study fruits are significant to lay a foundation for the BDS data application in atmosphere science.

搭载于FY-3C卫星上的GNOS是国际首台北斗系统（BDS）和GPS双系统GNSS掩星探测仪，并且配备了“超稳晶振”，使非差法附加相位计算成为可能。为了提高BDS掩星产品的精度，验证BDS和GPS掩星产品精度的一致性，本项目拟开展以下四个方面的研究。针对BDS轨道类型的特点，仿真分析BDS-LEO掩星事件全球分布特性；突破GPS/BDS及其组合LEO精密定轨的关键技术，完成GPS、BDS和GPS/BDS组合LEO卫星精密定轨结果误差特性分析；研究BDS掩星的单/非差法附加相位处理算法，分析BDS掩星非差法比单差法在精度与掩星事件数量上的提高程度；最后分析由于BDS轨道类型特点引起的LEO轨道和BDS卫星精度不同对掩星反演结果的影响。由于BDS掩星观测数据是国际上首次获取，因此基于BDS观测数据的掩星数据处理研究具有开创性意义，本文的研究将为BDS掩星在大气科学中的应用奠定基础。

FY-3C/GNOS是国际首台北斗系统（BDS）和GPS双系统GNSS掩星探测仪，并且配备了“超稳晶振”，因此可以进行非差法BDS掩星处理。本项目在以下几个方面展开了研究：①分析了BDS-LEO掩星事件全球分布特性，表明GEO掩星事件主要分布在高纬，IGSO掩星事件在中国和大洋洲区域分布密集；②完成了GPS/BDS及其组合的LEO卫星精密定轨结果误差特性分析，结果表明：单独使用GPS的FY3C/GNOS精密定轨3DRMS在3cm 左右，单独使用BDS的FY3C/GNOS精密定轨3DRMS能达到10cm，GPS/BDS组合的FY3C/GNOS精密定轨相比单独GPS的精密定轨提高了稳定性；③分析了BDS掩星非差法比单差法在精度与掩星事件数量上的提高程度及不同BDS轨道类型的掩星反演结果精度，结果表明：BDS-2非差法相比单差法的掩星事件数量提高了20%，GEO、IGSO两种掩星类型的弯曲角精度都与MEO掩星精度相当。本文的研究为BDS掩星在大气科学中的应用奠定了基础。