We present a power spectral analysis of two narrow annular regions near Jupiter's South Pole derived from data acquired by the Jovian Infrared Auroral Mapper instrument onboard NASA's Juno mission. In particular, our analysis focuses on the data set acquired by the Jovian Infrared Auroral Mapper M‐band imager (hereafter IMG‐M) that probes Jupiter's thermal emission in a spectral window centered at 4.8 μm. We analyze the power spectral densities of circular paths outside and inside of cyclones on images acquired during six Juno perijoves. The typical spatial resolution is around 55 km pixel⁻¹. We limited our analysis to six acquisitions of the South Pole from February 2017 to May 2018. The power spectral densities both outside and inside the circumpolar ring seem to follow two different power laws. The wave numbers follow average power laws of −0.9 ± 0.2 (inside) and −1.2 ± 0.2 (outside) and of −3.2 ± 0.3 (inside) and −3.4 ± 0.2 (outside), respectively, beneath and above the transition in slope located at ~2 × 10⁻³ km⁻¹ wave number. This kind of spectral behavior is typical of two‐dimensional turbulence. We interpret the 500 km length scale, corresponding to the transition in slope, as the Rossby deformation radius. It is compatible with the dimensions of a subset of eddy features visible in the regions analyzed, suggesting that a baroclinic instability may exist. If so, it means that the quasi‐geostrophic approximation is valid in this context.

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朱诺/ JIRAM对木星南极气旋周围区域的湍流功率谱

我们展示了木星南极附近两个狭窄环形区域的功率谱分析，这些光谱是通过NASA朱诺任务上的Jovian红外极光测绘仪仪器获得的数据得出的。特别是，我们的分析着重于Jovian红外极光映射器M波段成像仪（以下称为IMG-M）获取的数据集，该数据集在4.8μm中心的光谱窗口中探测木星的热辐射。我们分析了在六个朱诺周六周期间获得的图像上旋风内部和外部的圆形路径的功率谱密度。典型的空间分辨率约为55 km像素^-1。我们将分析限于2017年2月至2018年5月对南极的六次收购。.极环内外的功率谱密度似乎遵循两个不同的功率定律。波数分别遵循斜率过渡下方和上方的-0.9±0.2（内部）和-1.2±0.2（外部）以及-3.2±0.3（内部）和-3.4±0.2（外部）的平均功率定律位于〜2 ×  10 ^-3  km ^-1波数。这种光谱行为是二维湍流的典型特征。我们解释了500 km的长度标尺，它对应于坡度的过渡，作为Rossby变形半径。它与在所分析区域中可见的涡旋特征子集的尺寸兼容，表明可能存在斜压不稳定性。如果是这样，则表示在这种情况下拟地转近似是有效的。