The atmospheres of the four giant planets of our Solar System share a common and well-observed characteristic: they each display patterns of planetary banding, with regions of different temperatures, composition, aerosol properties and dynamics separated by strong meridional and vertical gradients in the zonal (i.e., east-west) winds. Remote sensing observations, from both visiting spacecraft and Earth-based astronomical facilities, have revealed the significant variation in environmental conditions from one band to the next. On Jupiter, the reflective white bands of low temperatures, elevated aerosol opacities, and enhancements of quasi-conserved chemical tracers are referred to as ‘zones.’ Conversely, the darker bands of warmer temperatures, depleted aerosols, and reductions of chemical tracers are known as ‘belts.’ On Saturn, we define cyclonic belts and anticyclonic zones via their temperature and wind characteristics, although their relation to Saturn’s albedo is not as clear as on Jupiter. On distant Uranus and Neptune, the exact relationships between the banded albedo contrasts and the environmental properties is a topic of active study. This review is an attempt to reconcile the observed properties of belts and zones with (i) the meridional overturning inferred from the convergence of eddy angular momentum into the eastward zonal jets at the cloud level on Jupiter and Saturn and the prevalence of moist convective activity in belts; and (ii) the opposing meridional motions inferred from the upper tropospheric temperature structure, which implies decay and dissipation of the zonal jets with altitude above the clouds. These two scenarios suggest meridional circulations in opposing directions, the former suggesting upwelling in belts, the latter suggesting upwelling in zones. Numerical simulations successfully reproduce the former, whereas there is a wealth of observational evidence in support of the latter. This presents an unresolved paradox for our current understanding of the banded structure of giant planet atmospheres, that could be addressed via a multi-tiered vertical structure of “stacked circulation cells,” with a natural transition from zonal jet pumping to dissipation as we move from the convectively-unstable mid-troposphere into the stably-stratified upper troposphere.

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我们如何理解巨行星大气的带/带环流？

我们太阳系的四颗巨行星的大气有一个共同的和被很好观察到的特征：它们每个都显示出行星带的模式，具有不同温度、成分、气溶胶特性和动力学的区域被带状区域中强烈的经向和垂直梯度隔开。 （即东西）风。来自来访航天器和地球天文设施的遥感观测揭示了从一个波段到另一个波段的环境条件的显着变化。在木星上，低温反射的白色带、气溶胶不透明度升高和准守恒化学示踪剂的增强被称为“区域”。相反，温度升高、气溶胶耗尽和化学示踪剂减少的较暗带被称为“带”。在土星上，我们通过它们的温度和风特性来定义气旋带和反气旋带，尽管它们与土星反照率的关系不像木星上那么清楚。在遥远的天王星和海王星上，带状反照率对比与环境特性之间的确切关系是一个活跃的研究课题。这篇综述试图将观测到的带和带的特性与（i）从涡角动量汇聚到木星和土星云层向东的带状急流中推断出的经向翻转以及湿对流活动的盛行进行调和。腰带；(ii) 从对流层上层温度结构推断出的相反的经向运动，这意味着纬向急流随高度高于云层而衰减和消散。这两种情景表明了相反方向的经向环流，前者表明带上升流，后者表明带上升流。数值模拟成功地再现了前者，而有大量观测证据支持后者。这为我们目前对巨行星大气带状结构的理解提出了一个悬而未决的悖论，这可以通过“堆叠环流单元”的多层垂直结构来解决，当我们从对流不稳定的对流层中层进入稳定分层的对流层上层。而有大量观察证据支持后者。这为我们目前对巨行星大气带状结构的理解提出了一个悬而未决的悖论，这可以通过“堆叠环流单元”的多层垂直结构来解决，当我们从对流不稳定的对流层中层进入稳定分层的对流层上层。而有大量观察证据支持后者。这为我们目前对巨行星大气带状结构的理解提出了一个悬而未决的悖论，这可以通过“堆叠环流单元”的多层垂直结构来解决，当我们从对流不稳定的对流层中层进入稳定分层的对流层上层。