Dynamical implications of Jupiter's tropospheric ammonia abundance
Dynamical implications of Jupiter's tropospheric ammonia abundance
复制标题
木星对流层氨丰度的动力学意义
DOI：
10.1016/j.icarus.2004.10.004
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发表时间：
2005
期刊：
影响因子：
3.2
通讯作者：
I. Pater
中科院分区：
文献类型：
--
作者：
A. Showman;I. Pater
地面无线电观测表明，木星的氨在全球范围内从0.6巴减少到至少4-6巴，相对于2.3倍太阳能的深度丰度，这一事实迄今无法解释。观测结果还表明，（一）带中的损耗大于带中的损耗，（二）最大的损耗发生在木星局部5 μm热点内，最近在无线电波长上探测到了这些热点。在这里，我们首先表明，全球枯竭及其带区的变化可以解释一个简单的模型与木星的云层环流的相互作用的湿对流。如果全球枯竭是动力学的起源，那么重要的端元模型的带区环流可以排除。接下来，我们表明，木星的5 μm热点的射电观测意味着，赤道波推断，导致热点诱导垂直包裹振荡的一个因素的压力在2巴附近的水平，这对热点动力学的重要限制。最后，使用空间分辨的无线电地图，我们表明，低纬度的功能超过104000公里的直径，如赤道羽流和大涡，也耗尽氨从0.6巴到至少2巴相对于3倍太阳的深度丰度。如果存在任何低纬度特征，其含有3倍太阳能的氨，达到0.6巴的氨凝结水平，那么它们的直径必须小于4000公里。
Groundbased radio observations indicate that Jupiter's ammonia is globally depleted from 0.6 bars to at least 4–6 bars relative to the deep abundance of ∼3 times solar, a fact that has so far defied explanation. The observations also indicate that (i) the depletion is greater in belts than zones, and (ii) the greatest depletion occurs within Jupiter's local 5-μm hot spots, which have recently been detected at radio wavelengths. Here, we first show that both the global depletion and its belt-zone variation can be explained by a simple model for the interaction of moist convection with Jupiter's cloud-layer circulation. If the global depletion is dynamical in origin, then important endmember models for the belt-zone circulation can be ruled out. Next, we show that the radio observations of Jupiter's 5-μm hot spots imply that the equatorial wave inferred to cause hot spots induces vertical parcel oscillation of a factor of ∼2 in pressure near the 2-bar level, which places important constraints on hot-spot dynamics. Finally, using spatially resolved radio maps, we demonstrate that low-latitude features exceeding ∼4000 km diameter, such as the equatorial plumes and large vortices, are also depleted in ammonia from 0.6 bars to at least 2 bars relative to the deep abundance of 3 times solar. If any low-latitude features exist that contain 3-times-solar ammonia up to the 0.6-bar ammonia condensation level, they must have diameters less than ∼4000 km.