Orbital change experiments with a Mars general circulation model
Orbital change experiments with a Mars general circulation model
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DOI：
10.1016/s0019-1035(02)00017-9
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发表时间：
2003
期刊：
影响因子：
3.2
通讯作者：
R. Haberle;J. Murphy;J. Schaeffer
中科院分区：
文献类型：
--
作者：
R. Haberle;J. Murphy;J. Schaeffer
我们使用火星大气环流模型来研究轨道变化对火星大气环流和气候系统的影响。实验在0° ~ 60°范围内对两种不同的近日点倾角进行了测量。每个实验都模拟了一个完整的火星年，假设大气中的尘埃分布和大气/帽系统中的CO2含量固定。我们发现，全球平均表面温度和压力下降，由于冬季极冠范围的增加，增加的透明度。季节性的CO2循环和至点环流的强度随着温度的增加而大大增强，因此全球沙尘暴可能在两个至点发生。强至环流的最显著特征是与Hadley环流的回流分支相联系的强烈低空急流的发展。模型表面应力被用来映射区域的首选灰尘升降，这是定义在每年的通缩潜力。对于目前的通货紧缩，模型预测的高通货紧缩潜力区域与Cantor等人的结果吻合得很好。s（2001，J. Geophys. Res.106，23653-23688）的观测，这给了我们一些信心，在模型的能力，以预测在哪里可能会发生电梯时，火星的轨道参数是不同的，比他们今天。在一般情况下，我们发现，尘埃升降潜力急剧增加，并在高湿度时，近日点与北方夏至重合是最大的。在一个周期内，模型全球年通缩潜力的范围从0°周期时的零点几毫米到60°周期时的近15毫米。当大气中的灰尘非常多时，可能会有更高的值。我们发现了一个很强的通缩潜力和表面热惯性之间的相关性：高通缩潜力的地区对应的高热惯性（高岩石丰度）的地区，低通缩潜力的地区对应的低热惯性（高灰尘/沙子丰度）的地区。此外，虽然首选的提升（高通缩潜力）的地区有所扩大，增加的湿度和尘埃负荷，塔尔西斯，阿拉伯半岛和极乐世界的中心部分显示没有显着的趋势，在任何高度或经度的近日点提升。因此，这些区域可能非常古老，是大气尘埃的长期净汇。这是地球的地形，通过它对表面压力和风力系统的影响，最终决定了尘埃的积聚。最后，如芬顿和理查森（2001，J. Geophys. Res.106，32885-32909），我们发现没有趋势的发展东南风在探路者网站的任何我们的轨道变化实验。这表明，格里利等人（2000年，地球物理学杂志）讨论的古代风况。Res.105，1829-1840）是由其他因素产生的，如极移。
We use a Mars general circulation model to examine the effect of orbital changes on the planet’s general circulation and climate system. Experiments are performed for obliquities ranging from 0° to 60° for two different longitudes of perihelion. Each experiment simulates a full Mars year assuming a fixed atmospheric dust distribution and fixed amount of CO2in the atmosphere/cap system. We find that global mean surface temperatures and pressures decline with increasing obliquity due to the increasing extent of the winter polar caps. The seasonal CO2cycle and intensity of the solstice circulation amplify considerably with increasing obliquity such that global dust storms are likely at both solstices. The most significant feature of the high obliquity solstice circulations is the development of an intense low-level jet associated with the return branch of the Hadley circulation. Model surface stresses are used to map regions of preferred dust lifting, which are defined in terms of an annual deflation potential. For the present obliquity, the model-predicted regions of high deflation potential are in good agreement with Cantor et al.’s (2001, J. Geophys. Res.106, 23653–23688) observations, which gives us some confidence in the model’s ability to predict where lifting might occur when Mars’ orbit parameters are different than they are today. In general we find that the dust lifting potential increases sharply with obliquity and is greatest at times of high obliquity when perihelion coincides with northern summer solstice. Over an obliquity cycle, the model global annual deflation potential ranges from several tenths of a millimeter at 0° obliquity to almost 15 mm at 60° obliquity. Much higher values are possible when the atmosphere is very dusty. We find a strong correlation between the deflation potential and surface thermal inertia: regions of high deflation potential correspond to regions of high thermal inertia (high rock abundance), and regions of low deflation potential correspond to regions of low thermal inertia (high dust/sand abundance). Furthermore, while the regions of preferred lifting (high deflation potential) expand somewhat with increasing obliquity and dust loading, the central parts of Tharsis, Arabia, and Elysium show no tendency for significant lifting at any obliquity or longitude of perihelion. These regions may therefore be very old and represent net long-term sinks for atmospheric dust. It is the topography of the planet, through its influence on surface pressure and wind systems, which ultimately determines where dust accumulates. Finally, as was found by Fenton and Richardson (2001, J. Geophys. Res.106, 32885–32909), we find no tendency for the development of east-southeasterly winds at the Pathfinder site for any of our orbital change experiments. This suggests that the ancient wind regime discussed by Greeley et al. (2000, J. Geophys. Res.105, 1829–1840) was produced by other factors, such as polar wander.