The Solar Wind and Interplanetary Magnetic Field at Mars

与地球、木星和土星不同，火星没有强大的行星磁场。然而，电离的火星高层大气与超音速太阳风的相互作用产生了感应磁层，对入射太阳风及其嵌入的行星际磁场（IMF）构成了导电障碍。由此产生的太阳风-磁层-电离层相互作用，受到局部地壳磁场的影响，与强磁化行星的相互作用大不相同，这是过去二十年来国际研究的焦点。在地球上，在L1拉格朗日点进行的连续太阳风和IMF测量揭示了磁层-电离层耦合系统的能量和质量输入，该系统受到行星际和地球磁场相对方向的强烈控制。然而，在了解磁化太阳风驱动器与火星磁层、电离层和大气响应之间的关系方面，最重要的挑战之一是缺乏此类上游数据。除了相对少数偶然的卫星会合外，上游参数通常是从代理数据推断出来的，有时需要对空间和/或时间变异性做出不切实际的假设，而这在陆地环境中是不可接受的。在这个项目中，学生将评估这些假设的可信度和影响，并通过数据分析和建模测试替代方法。项目目标包括：通过对现场磁场和等离子体测量的分析，描述火星上静态/背景太阳风和嵌入的IMF的变化特征。评估当前最先进的太阳风/IMF传播模型在估计火星环境中的等离子体速度、密度和磁场特性方面的有效性。探索新的预报技术，为火星和其他行星提供可靠的太阳风和IMF参数。

Unlike the Earth, Jupiter and Saturn, Mars lacks a strong planetary magnetic field. However, the interaction of the ionised Martian upper atmosphere with the supersonic solar wind generates an induced magnetosphere that presents a conductive obstacle to the incoming solar wind and its embedded interplanetary magnetic field (IMF). The resulting solar wind-magnetosphere-ionosphere interactions, modified by the contribution of localised crustal magnetic fields, are quite different to those at strongly magnetized planets and have been the focus of international research over the last two decades.At Earth, continuous solar wind and IMF measurements made at the L1 Lagrange point reveal the energy and mass inputs to the coupled magnetosphere-ionosphere system, controlled strongly by the relative orientation of the interplanetary and terrestrial magnetic fields. However, one of the foremost challenges in understanding the relationships between magnetised solar wind drivers and magnetosphere, ionosphere and atmospheric responses at Mars has been a scarcity of such upstream data. Except for a relatively small number of fortuitous satellite conjunctions, upstream parameters are usually inferred from proxy data, sometimes requiring unrealistic assumptions regarding spatial and/or temporal variability that would be unacceptable in the terrestrial context. In this project the student will assess the credibility and impact of such assumptions and test alternative methodologies through data analysis and modelling. Project goals include:1. To characterise the variability of the quiescent/background solar wind and the embedded IMF at Mars through an analysis of in situ field and plasma measurements.2. To assess how effective current state-of-the-art solar wind/IMF propagation models are at estimating the plasma speed, density and magnetic field properties in the Martian environment.3. To explore new forecasting techniques to provide reliable solar wind and IMF parameters at Mars and other planets.