Saturn's Zonal Winds at Cloud Level
Saturn's Zonal Winds at Cloud Level
复制标题
土星云层的纬向风
DOI：
10.1006/icar.2000.6449
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发表时间：
1999
期刊：
影响因子：
3.2
通讯作者：
P. Sada
中科院分区：
文献类型：
--
作者：
A. Sánchez‐Lavega;J. F. Rojas;P. Sada
我们提出了一个新的云运动测量在土星的大气层中的旅行者1号和2号图像的分析，并定义了一个名义上的纬向风速与纬度的云顶水平，可作为参考即将到来的卡西尼使命。与以前的研究相比，改进包括：（i）使用的风矢量数量增加一倍，（ii）云示踪剂的独立测量，（iii）扩大纬度覆盖范围，（iv）严格的误差控制和评估，以及（v）新的纬向平均方法。平均纬向风速在纬度81°至−71°（行星图）范围内以0.5°为步长给出，由于环阴影的影响，间隔在0°和−10°之间。这项研究还包括以前没有描述过的赤道和南半球云系形态和运动的研究。我们给出了一个历书（运动方程）的几个长寿的功能，可以观察到，如果他们生存，直到卡西尼号到达土星。纬向风廓线的长期行为进行了研究，通过比较它与一套完整的风速汇编从历史和现代的地面和HST观测。显著的变化，注意到赤道急流之间的这一套和名义旅行者的个人资料。我们详细讨论了这种差异的可能来源。
We present an analysis of new cloud motion measurements in Saturn's atmosphere from Voyager 1 and 2 images and define a nominal zonal wind velocity vs latitude profile for the cloud top level that can be used as reference for the upcoming Cassini mission. Improvements over previous studies include: (i) twice the number of wind vectors used, (ii) independent measurements of cloud tracers, (iii) extended latitudinal coverage, (iv) strict error control and evaluation, and (v) a new zonal averaging methodology. Mean zonal wind velocities are given for the latitude range 81° to −71° (planetographic) in steps of 0.5° with a gap between 0° and −10° due to ring shadowing. This research also includes the study of the morphology and motions of cloud systems in the equator and in the southern hemisphere which have not been described previously. We give an ephemeris (motion equation) for several long-lived features that could be observable if they survive until Cassini arrives on Saturn. The long-term behavior of the zonal wind profile is studied by comparing it with a complete set of wind velocities compiled from historical and modern ground-based and HST observations. Significant changes are noted in the equatorial jet between this set and the nominal Voyager profile. We discuss in detail the possible origin for such differences.