不同源区太阳风在内日球层的径向演化及其随太阳活动周变化

太阳风是太阳持续向外喷发的高速磁化等离子体流，是太阳向外输运物质能量的重要方式，决定了行星际空间的性质，影响各行星空间环境。在日球层传播过程中太阳风是时刻演化的。对太阳风径向演化的观测研究，可为太阳风传播模型提供重要观测依据，有助于更好的理解太阳风对行星空间环境的影响。前人对太阳风径向演化的研究主要按速度分类，并且未关注其是否随太阳活动周变化。目前0.3AU以内太阳风径向演化的观测知识是严重缺乏的。最新探测器PSP和Solar Orbiter为研究0.3AU以内太阳风的径向演化提供契机。本项目拟基于PSP、Solar Orbiter、STEREO-A、WIND、ACE的多点联合观测，用新的思路来研究太阳风的径向演化，即按照源区分类并区分太阳活动周不同阶段，研究各源区太阳风在内日球层的径向演化规律及其随太阳活动周的变化，有望解决目前太阳风径向演化观测研究中有争议的问题。

The solar wind is a stream of magnetized plasma released from the Sun and an important way to transport material and energy from the sun to the heliosphere. The solar wind determines the nature of interplanetary space and affects the space environment of planets. The solar wind is evolving during its journey in the heliosphere. The observational study of the radial evolution of the solar wind can provide important constraint for the solar wind propagation model and help to better understand the solar wind's influence on the planetary space environment. Previous studies on the radial evolution of the solar wind were mainly classified by velocity and did not pay attention to whether it changed with the solar cycle. Moreover, the observational knowledge of the radial evolution of solar wind within 0.3 AU is lacking. Parker solar probe (PSP;<0.25AU) and Solar Orbiter (0.28-1.4AU) provide an opportunity to study the radial evolution of Solar wind within 0.3 AU. Based on the observation from PSP, Solar Orbiter, STEREO, WIND, and ACE, this project will take advantage of the multipoint joint observation to study the radial evolution of solar wind from different sources in the inner heliosphere and how it changes with the Solar cycle. It is expected to solve contentious issues in the radial evolution of the solar wind.