Hybrid satellite constellations for high-resolution atmospheric modeling and sounding (HOLMES)

全球卫星导航系统（GNSS）不仅可以用于定位和导航，还可以用于观测大气中的温度和水蒸气、电离层电子含量、精确点坐标和同震变形。地球物理的一个关键应用是大气参数反演，用于天气事件的预测和监测。由于目前大多数应用的大气产品仍然仅基于GPS观测数据，其时空分辨率非常有限。包括新的全球导航卫星系统，如欧洲的伽利略和中国的北斗，以及低地球轨道（LEO）卫星星座的发展，这些卫星与更高轨道的卫星有测距联系，也可能与地面联系，为地球科学应用开辟了广阔的前景。传统中地球轨道（MEO）导航卫星、地球静止轨道（GEO）卫星、倾斜地球同步轨道（IGSO）卫星和低轨道卫星观测几何形状快速变化的互补轨道特性，有望显著增强对流层和电离层参数的估计，从而更详细地描述大气的垂直和水平特性。项目主要研究建立MEO/GEO/IGSO/LEO综合处理模式，用于大气参数估算和高精度、高分辨率大气产品的推导。本项目将解决以下几个关键方面：•将开发一个综合GPS、北斗、伽利略和LEO数据处理的数学模型，这将为后续大气参数的估计和分析奠定基础。•利用上述综合处理模式实现对流层天顶延迟和水平梯度的高分辨率快速反演方法，并研究其能力。•将开发利用低轨道卫星增强GNSS电离层传感和建模的概念，并将研究监测小尺度空间天气事件的效益。

Global Navigation Satellite Systems (GNSS) can not only be used for positioning and navigation, but also for observing the temperature and water vapor in the atmosphere, the ionospheric electron content, precise point coordinates, and coseismic deformations. A geophysical key application is atmospheric parameter inversion for the prediction and monitoring of weather events. Since currently most operational atmospheric products are still based on GPS only observation data, their spatiotemporal resolution is very limited. Including new GNSS, such as the European Galileo and the Chinese BeiDou as well as the development of Low Earth Orbit (LEO) satellite constellations with ranging links to satellites in higher orbits and potentially also to the ground opens promising perspectives for geoscience applications. The complementary orbit properties of conventional Medium Earth Orbit (MEO) navigation satellites, Geostationary Earth Orbit (GEO) satellites, Inclined Geo-Synchronous Orbit (IGSO) satellites, and LEO satellites with their rapidly changing observation geometry are expected to significantly enhance the estimation of tropospheric and ionospheric parameters, so that a more detailed description of the vertical and horizontal properties of the atmosphere can be derived. The proposed project will focus on formulating an integrated MEO/GEO/IGSO/LEO processing model for atmospheric parameter estimation and the derivation of high precision and high resolution atmospheric products. The following key aspects will be addressed in this project: • A mathematical model for integrated GPS, BeiDou, Galileo, and LEO data processing will be developed, which will form the basis for the subsequent estimation and analysis of atmospheric parameters. • Methods for the rapid inversion of high-resolution tropospheric zenith delays and horizontal gradients using the above integrated processing model will be implemented and their capabilities will be studied. • Concepts for the augmentation of GNSS ionospheric sensing and modeling with LEO satellites will be developed and the benefit for monitoring small-scale space weather events will be investigated.