Cooling of the Martian thermosphere by CO2 radiation and gravity waves: An intercomparison study with two general circulation models
Cooling of the Martian thermosphere by CO2 radiation and gravity waves: An intercomparison study with two general circulation models
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DOI：
10.1002/2015je004802
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
A. Medvedev;Francisco Gonz'alez-Galindo;Erdal Yiğit;A. Feofilov;F. Forget;P. Hartogh
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文献类型：
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作者：
A. Medvedev;Francisco Gonz'alez-Galindo;Erdal Yiğit;A. Feofilov;F. Forget;P. Hartogh
观测表明，火星的低热层（100-140公里）比目前的大气环流模型（GCM）所能再现的温度低40 K。模型中缺少的物理过程的可能候选者是更大丰度的原子氧，促进更强的CO2辐射冷却和重力波的热效应。使用两个最先进的火星GCM，Météorologie Dynamique和马克斯普朗克研究所模型，自洽地覆盖了从表面到热层的大气，研究了这些物理机制。模拟表明，具有足够大的原子氧丰度的CO2辐射冷却和重力波引起的冷却可以单独导致低热层中高达40 K的低温。考虑到这两种机制，在高纬度地区产生了更强的冷却作用。然而，辐射冷却效应在中层顶以上达到峰值，而重力波冷却率则随高度不断增加。虽然这两种机制同时起作用，但这些特性可能有助于进一步量化它们在未来观测中的相对贡献。
Observations show that the lower thermosphere of Mars (∼100–140 km) is up to 40 K colder than the current general circulation models (GCMs) can reproduce. Possible candidates for physical processes missing in the models are larger abundances of atomic oxygen facilitating stronger CO2 radiative cooling and thermal effects of gravity waves. Using two state‐of‐the‐art Martian GCMs, the Laboratoire de Météorologie Dynamique and Max Planck Institute models that self‐consistently cover the atmosphere from the surface to the thermosphere, these physical mechanisms are investigated. Simulations demonstrate that the CO2 radiative cooling with a sufficiently large atomic oxygen abundance and the gravity wave‐induced cooling can alone result in up to 40 K colder temperature in the lower thermosphere. Accounting for both mechanisms produce stronger cooling at high latitudes. However, radiative cooling effects peak above the mesopause, while gravity wave cooling rates continuously increase with height. Although both mechanisms act simultaneously, these peculiarities could help to further quantify their relative contributions from future observations.