基于多观测数据的时变背景太阳风数值模拟及其结果评估

Time-dependent 3D MHD modeling driven by multiple-observational-data is a research field of scientific significance and great practicability. This project will design the new approaches that constrain the numerical model to vector photospheric magnetograms and the data derived from the model of the surface flux transport (SFT) and the differential emission measure tomography (DEMT), and develop a new multiple-observational-data-based magnetohydrodynamic (MHD) model for the time-dependent solar wind background. With the help of the newly-developed model and the ensemble forecasting methods, the project will investigate the capability of the model to quantitatively reproduce the spatial and temporal variations of in-situ observations for the solar wind background. The project will also probe how various factors affect the numerical results, focusing on the influence of time cadences of input magnetograms on the simulated results and the specification of the optimal time cadence in simulating the evolution of the solar wind background. The project will inaugurate the comparison of the large-scale heliospheric structures between the images synthesized from the modeled results and observed from heliospheric imagers by developing new comparative analysis methods. By using the developed model, the project will investigate the evolutions of coronal structures of coronal holes, coronal streamers, pseudo-streamers, and non-potential field configurations, and interplanetary structures of the streamer interaction regions (SIR) and the heliospheric current sheet (HCS). The project will enhance the capability of the data-driven model to reproduce time-dependent solar wind background, and thus lay the foundations for numerical space weather forecasting by using the data-driven MHD models.

面向多观测数据驱动的时变三维太阳风模拟研究这一具有重要科学和应用价值的研究领域，利用矢量磁场以及EUV成像观测，结合表面通量传输(SFT)模型和微分辐射度层析(DEMT)反演方法等设计约束模型的新方法，发展多观测数据驱动的三维MHD背景太阳风新模型。借助行星际空间中不同位置的局地观测和太阳风模拟结果定量评估指标，建立基于多卫星数据的背景太阳风集合预报新方法。进而对模型再现行星际背景太阳风参数的时间和空间变化的能力做出定量评估，考察模型中各个因素对模拟结果的影响程度，确定与日冕行星际背景结构演化时间尺度相符的最优数据输入间隔。建立行星际MHD模拟结果与日球成像仪观测对比分析的新方法。本项目对冕洞、冕流带和伪冕流带等大尺度日冕结构的时间演化、日冕中产生的非势场结构及其演化、流相互作用区、日球电流片等行星际结构时间演化进行研究，从而提升数据驱动的时变背景太阳风模型重现观测的能力。

本项目以发展多观测数据约束的三维MHD背景太阳风新模型和基于多卫星数据建立背景太阳风模型模拟结果定量评估方法为重点，主要开展了以下研究工作：研制了多种观测约束的三维MHD太阳风模型，重构的背景太阳风参数再现了位于不同日心距离的太阳风观测飞船的就位观测；利用数据驱动的CESE-HLLD背景太阳风模式，建立了基于多飞船就位观测数据和多种度量指标对三维MHD背景太阳风模式的模拟结果进行多点综合验证的定量评估方法；将多种经验模型和1AU的观测统计相结合，建立了数据驱动的可较准确预报行星际背景磁场南北向分量的太阳风模型；建立日冕物质抛射的行星际MHD模拟结果与日球成像仪观测对比分析的新方法，重现了日冕仪和日球成像仪观测到的激波及CME的演化过程。在该项目支持下，项目组共发表科研论文22篇，其中21篇为SCI收录。