论文标题
联合磁性和重力测量探测气体巨头的深层层流量
Combined magnetic and gravity measurements probe the deep zonal flows of the gas giants
论文作者
论文摘要
在过去的几年中，土星的Cassini任务和木星的Juno任务都以两个天然气巨头的重力和磁场的前所未有的精度提供了测量。使用重力测量值，发现在气体巨头云级别上观察到的强层流很可能会将数千公里延伸到行星内部。但是，仅根据定义，仅重力测量值是质量的整合度量，不能高度确定流动的确切垂直结构。考虑到土星的最近的Cassini磁场测量以及木星磁场的过去世俗变化，我们在这些行星上观察到的Zonal流动的垂直衰减曲线上获得了额外的物理约束。我们组合的重力磁性分析表明，土星（木星）上的云水平的风很少腐烂，即在正视上，直至约7,000〜km（2,000〜 km）的深度，然后在半导体区域迅速衰减，在接下来的1,000 km（600 km）的价值中，众所周知，这是众所周知的1,000 km（600 km）的数量。这些结果表明，没有重要的机制可以使外部中性区域的流动衰减，并且与半导体区域中磁场的相互作用可能在流量的衰减中起核心作用。
During the past few years, both the Cassini mission at Saturn and the Juno mission at Jupiter, provided measurements with unprecedented accuracy of the gravity and magnetic fields of the two gas giants. Using the gravity measurements, it was found that the strong zonal flows observed at the cloud-level of the gas giants are likely to extend thousands of kilometers deep into the planetary interior. However, the gravity measurements alone, which are by definition an integrative measure of mass, cannot constrain with high certainty the exact vertical structure of the flow. Taking into account the recent Cassini magnetic field measurements of Saturn, and past secular variations of Jupiter's magnetic field, we obtain an additional physical constraint on the vertical decay profile of the observed zonal flows on these planets. Our combined gravity-magnetic analysis reveals that the cloud-level winds on Saturn (Jupiter) extend with very little decay, i.e., barotropically, down to a depth of around 7,000~km (2,000~km) and then decay rapidly in the semiconducting region, so that within the next 1,000 km (600~km) their value reduces to about 1\% of that at the cloud-level. These results indicate that there is no significant mechanism acting to decay the flow in the outer neutral region, and that the interaction with the magnetic field in the semiconducting region might play a central role in the decay of the flows.
