Prior analyses of oceanic magnetic induction within Jupiter's large icy moons have assumed uniform electrical conductivity. However, the phase and amplitude responses of the induced fields will be influenced by the natural depth‐dependence of the electrical conductivity. Here, we examine the amplitudes and phase delays for magnetic diffusion in modeled oceans of Europa, Ganymede, and Callisto. For spherically symmetric configurations, we consider thermodynamically consistent interior structures that include realistic electrical conductivity along the oceans' adiabatic temperature profiles. Conductances depend strongly on salinity, especially in the large moons. The induction responses of the adiabatic profiles differ from those of oceans with uniform conductivity set to values at the ice–ocean interface, or to the mean values of the adiabatic profile, by more than 10% for some signals. We also consider motionally induced magnetic fields generated by convective fluid motions within the oceans, which might optimistically be used to infer ocean flows or, pessimistically, act to bias the ocean conductivity inversions. Our upper‐bound scaling estimates suggest this effect may be important at Europa and Ganymede, with a negligible contribution at Callisto. Based on end‐member ocean compositions, we quantify the magnetic induction signals that might be used to infer the oxidation state of Europa's ocean and to investigate stable liquids under high‐pressure ices in Ganymede and Callisto. Fully exploring this parameter space for the sake of planned missions requires thermodynamic and electrical conductivity measurements in fluids at low temperature and to high‐salinity and pressure as well as modeling of motional induction responses.

中文翻译：

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木星海月卫星的磁感应响应，包括绝热对流的影响

先前对木星大型冰冷月球内的海洋磁感应强度的分析都假定电导率均匀。但是，感应场的相位和幅度响应将受到电导率的自然深度依赖性的影响。在这里，我们研究了欧罗巴，木卫三和卡利斯托的模拟海洋中磁扩散的幅度和相位延迟。对于球形对称配置，我们考虑热力学一致的内部结构，其中包括沿海洋绝热温度曲线的实际电导率。电导在很大程度上取决于盐度，尤其是在大卫星中。绝热剖面的感应响应不同于将电导率统一设置为冰-海洋界面值的海洋的感应响应，或绝热曲线的平均值，对于某些信号，超过10％。我们还考虑了海洋中对流流体运动产生的运动感应磁场，该磁场可能被乐观地用来推断海洋流量，或者悲观地说，是用来偏向海洋电导率反转。我们的上限缩放估计值表明，此影响在欧罗巴和木卫三可能很重要，而对Callisto的贡献则微不足道。根据最终成员的海洋成分，我们对可能用于推断欧罗巴海洋氧化态并研究盖尼迈德和卡利斯托的高压冰下稳定液体的磁感应信号进行量化。