Convection in Thin Shells of Icy Satellites: Effects of Latitudinal Surface Temperature Variations
Convection in Thin Shells of Icy Satellites: Effects of Latitudinal Surface Temperature Variations
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DOI：
10.1029/2018je005799
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发表时间：
2019-08
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影响因子：
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通讯作者：
M. Weller;L. Fuchs;T. Becker;K. Soderlund
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文献类型：
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作者：
M. Weller;L. Fuchs;T. Becker;K. Soderlund
我们使用薄壳对流的三维数值实验来探索太阳辐射的预期纬度变化可能对对流产生的影响。我们发现，上升流赤道地区和下降流极地地区，连接到较高和较低的表面温度（Ts），分别是首选的全球流动模式。由于Ts的梯度，边界层厚度从赤道低压到极地高压变化，并建立了极向流场。一个具有两个半球尺度对流单体的Hadley单体型结构出现，热流沿赤道沿着增强，向极地抑制。在基底加热和混合加热、等粘粘度和温度依赖粘度、对流活力和不同程度的Ts变化的范围内，极向输送型表现出稳健性。我们的研究结果表明，在Ts的纬度变化是一个重要的影响对流内的薄冰壳的外卫星，变得越来越重要，太阳光度的增加。变Ts模型预测低热流和更压缩的制度，在更高的纬度，更高的热流和赤道附近的伸展制度。在冰壳内，哈德利式流动可能会导致大规模的各向异性冰特性，这些特性可能会通过未来的地震或电磁观测来检测。
We use three‐dimensional numerical experiments of thin shell convection to explore what effects an expected latitudinal variation in solar insolation may have on a convection. We find that a global flow pattern of upwelling equatorial regions and downwelling polar regions, linked to higher and lower surface temperatures (Ts), respectively, is preferred. Due to the gradient in Ts, boundary layer thicknesses vary from equatorial lows to polar highs, and polar oriented flow fields are established. A Hadley cell‐type configuration with two hemispheric‐scale convective cells emerges with heat flow enhanced along the equator and suppressed poleward. The poleward transport pattern appears robust under a range of basal and mixed heating, isoviscous and temperature‐dependent viscosity, vigor of convection, and different degrees of Ts variations. Our findings suggest that a latitudinal variation in Ts is an important effect for convection within the thin ice shells of the outer satellites, becoming increasingly important as solar luminosity increases. Variable Ts models predict lower heat flow and a more compressional regime near downwellings at higher latitudes, and higher heat flow and a more extensional regime near the equator. Within the ice shell, Hadley style flow could lead to large‐scale anisotropic ice properties that might be detectable with future seismic or electro‐magnetic observations.