Inverse insolation dependence of Venus' cloud-level convection
Inverse insolation dependence of Venus' cloud-level convection
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DOI：
10.1016/j.icarus.2013.10.012
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发表时间：
2014-01-15
期刊：
影响因子：
3.2
通讯作者：
Ando, Hirold
中科院分区：
文献类型：
--
作者：
Imamura, Takeshi;Higuchi, Takehito;Ando, Hirold
人们普遍认为，行星大气中的对流在低纬度地区和白天增强，因为那里的太阳辐射很强。在这里，我们证明，使用当地的对流模型，这种趋势是逆转金星的云级对流，这是由上涌的红外辐射加热的云底驱动。金星稠密的低层大气是一个热库，其温度在大尺度动力学的作用下水平均匀，因此上涌的红外线通量几乎均匀地加热了整个行星的云底。由于太阳辐射优先加热云的上部，并对大气产生稳定的影响，对流在低纬度和白天相对受到抑制。在数值模式中看到的逆日照依赖解释了对流层深度和重力波活动的纬度依赖性的观测。在金星和多云系外行星的气候建模中，应该考虑这项研究中提出的机制。红外加热和太阳加热的相反作用的组合如何决定对流活动的全球分布是一个具有普遍意义的问题。一个长寿命的金星气球漂浮在云层高度将有助于理解这些动力学过程和相关的物质传输。(C)2013 Elsevier Inc. All rights reserved.
It is generally accepted that convection in planetary atmospheres is enhanced in low latitudes and in the daytime where incoming solar radiation is intense. Here we demonstrate, using a local convection model, that this tendency is reversed for Venus' cloud-level convection, which is driven by heating of the cloud base by upwelling infrared radiation. The dense lower atmosphere of Venus serves as a heat reservoir, whose temperature is horizontally well homogenized by large-scale dynamics, and thus upwelling infrared flux heats the cloud base almost equally over the entire planet. Since solar radiation preferentially heats the upper part of the cloud and has a stabilizing influence on the atmosphere, convection is relatively suppressed in low latitudes and in the daytime. The inverse insolation dependence seen in the numerical model explains observations of the latitudinal dependence of the convective layer depth and the gravity wave activity. The mechanism suggested in this study should be taken into account in climate modeling of Venus and cloudy exoplanets. How the combination of the opposite effects of the infrared heating and the solar heating determines the global distribution of the convective activity is an issue of universal importance. A long-lifetime Venus balloon floating at cloud heights would be useful for understanding these dynamical processes and the associated material transport. (C) 2013 Elsevier Inc. All rights reserved.