面向空间态势感知需求的高层大气密度扰动规律建模研究

The ability of space situational awareness is a kind of national strategic needs of our country in the field of military and civil space, in which one of the difficulties is that there are significant errors in the upper atmospheric density model during solar and geomagnetic bursts. The project focuses on the upper atmosphere (thermospheric neutral gas) which range from 120km to 550km above the ground. When the solar flare or coronal mass ejection events occurred, amount of high-energy charged particles would drive server geomagnetic and ionospheric storms, causing distinct changes of atmospheric temperature, composition and total mass density, and finally bringing negative effects on satellites operation, space tracking and control mission, as well as collision avoidance of space debris..In this project, the observations on the air drag or density from five satellite missions, such as CHAMP, GRACE, GOCE, SWARM, and TIMED are adopted. Firstly, select about 80 solar and magnetic storms during 2002-2017 as samples. Then, study on the variation of atmospheric density in these events, and summarize their common features through comparison and statistics among multi-satellites and multi-samples. On basis of these results, we can construct an empirical model which is only suitable for the period of space environment disturbance, and then evaluate the effect of solar and magnetic storms on the LEO orbits. These achievements of the project will overcome the shortcomings of the present long-term average model and reduce the model error during the solar burst and magnetic storm time, improving the accuracy of orbit calculation for satellites and debris in LEO region. On the other hand, the detail characteristics discovered from observations with high temporal and spatial resolution will be helpful to promote the in-depth understanding on the laws of coupled interaction between the solar-terrestrial space environment and upper atmosphere.

空间态势感知能力，是我国在军事和民用航天领域的一个重要战略需求，它依赖于高精度的轨道确定和预报技术，难点之一是高层大气密度模型在太阳和地磁爆发时存在显著误差。当太阳发生耀斑、日冕物质抛射等剧烈活动时，高能带电粒子激发地球磁场和电离层的剧烈扰动，引发大气温度、成分、密度的复杂变化。实践表明，现有的模型都不能准确刻画和预测这种变化。.本项目将利用CHAMP, GRACE, GOCE, SWARM, TIMED等卫星的大气阻力和密度资料，选择2001-2017年80余次太阳和地磁爆发事件为样本，以多卫星、多事例的对比验证和统计分析为手段，定量描述120-550km范围内的高层大气大气密度变化的特征，建立一个适用于空间环境扰动期的大气密度模型。研究成果将弥补长期平均大气模型的不足，提高近地人造天体的轨道计算精度；并为日地空间环境研究提供高分辨率、全纬度覆盖的高层大气观测证据。

基于2001~2021年的CHAMP、GRACE-A和SWARM-C星载加速仪反演的大气密度资料，与SOHO卫星的极紫外测量，PCN、ap和Dst地磁指数，围绕太阳极紫外辐射、射电辐射、地磁爆发等空间环境扰动因素，通过个例分析与对比，以及大量事件的统计，研究了太阳极紫外辐射、太阳辐射27天短期震荡、地磁爆发对大气密度的影响，包括响应时间、整体振幅和空间差异（地方时/经度、纬度和高度等），证实了太阳极紫外辐射对全球大气密度的主导作用，且密度延迟时间约18小时，在日间的作用显著超过夜间，高度越低作用越显著等。从约200次地磁爆发事件的大气观测资料中确认了大气密度响应的定量和细节特征，例如昼夜涨幅差异和南北半球不对称，基于这些成果开展了空间环境剧烈扰动期大气密度建模研究，构建了模型框架，并进行了大量参数拟合试验，取得了较好的收敛效果。