Mechanisms of Jet Formation on the Giant Planets
Mechanisms of Jet Formation on the Giant Planets
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DOI：
10.1175/2010jas3492.1
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发表时间：
2010-11-01
影响因子：
3.1
通讯作者：
Schneider, Tapio
中科院分区：
文献类型：
--
作者：
Liu, Junjun;Schneider, Tapio
巨行星大气呈现出不同速度和宽度的交替的顺行（向东）和逆行（西向）喷流，赤道喷流在木星和土星上顺行，在天王星和海王星上逆行。喷流被不同地认为是由高层大气的差异辐射加热或从内部深处发出的固有热通量驱动的。然而，现有模型无法以能量一致的方式解释巨行星上不同的流动配置。这里是三维一般环流模型表明，如果考虑到它们的辐射加热和固有热通量的差异，不同的流动配置可以通过巨行星上普遍存在的机制来再现。赤道急流是顺行还是逆行取决于深层固有热通量是否足够强，以至于对流层上层并在那里产生强烈的赤道罗斯贝波。如果对流罗斯贝波产生强烈且低纬度角动量通量发散，则会产生顺行赤道急流。赤道以外产生的斜压涡流足够弱（木星和土星） 如果对流罗斯贝波产生较弱或不存在（天王星）或由于斜压涡流而产生的低纬度角动量通量散度足够强（海王星），就会产生逆行赤道急流。垂直剪切模拟具有与巨行星观测结果一致的闭合能量和角动量平衡它们表现出的温度结构与观测到的非常相似，并对尚未观测到的流动和温度结构进行了预测
The giant planet atmospheres exhibit alternating prograde (eastward) and retrograde (westward) jets of different speeds and widths with an equatorial jet that is prograde on Jupiter and Saturn and retrograde on Uranus and Neptune The Jets are variously thought to be driven by differential radiative heating of the upper atmosphere or by intrinsic heat fluxes emanating from the deep interior However existing models cannot account for the different flow configurations on the giant planets in an energetically consistent manner Here a three dimensional general circulation model is used to show that the different flow configurations can be reproduced by mechanisms universal across the giant planets if differences in their radiative heating and intrinsic heat fluxes are taken into account Whether the equatorial jet is prograde or retrograde depends on whether the deep intrinsic heat fluxes are strong enough that convection penetrates into the upper troposphere and generates strong equatorial Rossby waves there Prograde equatorial Jets result if convective Rossby wave generation is strong and low latitude angular momentum flux divergence owing to baroclinic eddies generated off the equator is sufficiently weak (Jupiter and Saturn) Retrograde equatorial Jets result if either convective Rossby wave generation is weak or absent (Uranus) or low latitude angular momentum flux divergence owing to baroclinic eddies is sufficiently strong (Neptune) The different speeds and widths of the off equatorial jets depend among other factors on the differential radiative heating of the atmosphere and the altitude of the Jets which are vertically sheared The simulations have closed energy and angular momentum balances that are consistent with observations of the giant planets They exhibit temperature structures closely resembling those observed and make predictions about as yet unobserved aspects of flow and temperature structures