论文标题
对流的伽利亚海洋中的磁诱导
Magnetic Induction in Convecting Galilean Oceans
论文作者
论文摘要
迄今为止，木星大冰卫星中推定的海洋中磁性诱导的分析已经假设在建模的海洋中均匀的电导率。但是，诱导场的相位和振幅响应将受到海洋对流绝热温度曲线的增加的电导率的影响。在这里，我们检查了欧罗巴，甘卫姆和卡利斯托海洋建模海洋中磁扩散的幅度和相位滞后。我们将分析限制为球体对称的构型，基于自洽的热力学处理内部结构，这解释了对流海洋中电导率的变化（Vance等，2018）。数值方法考虑了数十个径向层。在许多情况下，绝热电导率轮廓的诱导响应与冰山界面或绝热谱的平均值的均匀电导率的诱导响应在许多情况下都超过10％。此外，我们考虑了可以用来直接探测海洋流动的海洋流体运动产生诱导的磁场（例如Chave，1983; Tyler，2011; Minami，2017）。假设湍流对流（Soderlund等，2014），我们发现这些信号可以在低纬度的诱导信号中占主导地位，这突显了在磁性诱导研究中对空间覆盖的需求。基于末端成员的海洋成分（Zolotov，2008; Zolotov＆Kargel，2009），我们量化了可用于推断欧罗巴海洋的氧化状态的残留磁感应信号，并在Ganymede和Callisto中调查了高压冰的内外稳定液体。为了计划的任务，充分探索此参数空间需要在低温以及高盐度和压力下进行流体的电导率测量。
To date, analyses of magnetic induction in putative oceans in Jupiter's large icy moons have assumed uniform conductivity in the modeled oceans. However, the phase and amplitude response of the induced fields will be influenced by the increasing electrical conductivity along oceans' convective adiabatic temperature profiles. Here, we examine the amplitudes and phase lags for magnetic diffusion in modeled oceans of Europa, Ganymede, and Callisto. We restrict our analysis to spherically symmetric configurations, treating interior structures based on self-consistent thermodynamics, which account for variations in electrical conductivity with depth in convective oceans (Vance et al., 2018). The numerical approach considers tens of radial layers. The induction response of the adiabatic conductivity profile differs from oceans with uniform conductivity based on the ice-ocean interface or the mean value of the adiabatic profile by more than 10% in many cases. In addition, we consider the generation of induced magnetic fields by oceanic fluid motions that might be used to probe the ocean flows directly (e.g., Chave, 1983; Tyler, 2011; Minami, 2017). Assuming turbulent convection (Soderlund et al., 2014), we find that these signals can dominate induction signal at low latitudes, which underscores the need for spatial coverage in magnetic induction investigations. Based on end-member ocean compositions (Zolotov, 2008; Zolotov & Kargel, 2009), we quantify the residual magnetic induction signals that might be used to infer the oxidation state of Europa's ocean and to investigate stable liquids within and under high-pressure ices in Ganymede and Callisto. Fully exploring this parameter space for the sake of planned missions requires electrical conductivity measurements in fluids at low temperature and to high salinity and pressure.
