Effect of orbital parameters on the habitability on planets

轨道参数对行星宜居性的影响

• 批准号: 13640435
• 负责人: ABE Yutaka
• 金额: $ 2.11万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640435/
• 关键词: Freezing; Snowball Earth; Spin Obliquity; Aqua-planet; Land-planet; Solar flux; Ice-Albedo-Feedback; スノーボール・アイス

The condition for the occurrence of a completely frozen state (a "snow-ball" state) is investigated with a general circulation model for both a land planet case (a wet planet without fixed ocean) and an aqua planet (a planet entirely covered by an ocean) with a particular reference to the obliquity. Results : 1. A land planet shows stronger resistance to the com-plete freezing than an aqua planet. 2. Both land and aqua planets in an oblique regime show stronger resis-tance to the complete freezing than those in an upright regime. However, the dependence on the obliquity is not clear within the upright regime. 3. On a land planet in an oblique regime, low latitude area is more suscep-tible to freezing than the mid latitude area. Thus, there is a good chance of low-latitude-only freezing (freezing of low latitude without freezing the entire planet) of a land planet. 4. On an aqua planet with high obliquity, low latitude freezing occurs at lower solar constant than on a land planet with h … More igh obliquity. The range of the solar constant that yields low-latitude-only freezing is much narrower on an aqua planet than that on a land planet. Thus, low-latitude-only freezing is unlikely on an aqua planet. Implications for the paleo-Mars : 1. In order to keep a wet ground at the low latitude area of paleo-Mars, the planet must be in the oblique regime, or with oceans. Under such conditions, however, the low latitude is relatively easily covered by permanent snow. Thus, it is more difficult to keep unfrozen wet surface on low latitude than to keep Mars from the completely frozen state under the condition of the present obliquity. 2. If the obliquity changed significantly while Martian water cycle was active and the average temperature was de-creasing steadily, there must have been a period while only the low latitude area is covered by permanent snow. It is an interesting question whether we can find such evidence from geological records. Implication for the Habitability on a Planet : 1. A water rich aqua planet may not be the best place for life, and a land planet with some water may be better than an aqua planet, because an aqua planet easily falls in a completely frozen state. 2. It is a difficult question whether high obliquity or low obliquity planet is prefer-able. A high obliquity planet is resistive to the complete freezing, but experiences severe seasonal change. The calmest climate is found on 45° obliquity aqua planet. Less

对于陆地行星(没有固定海洋的湿行星)和水行星(完全被海洋覆盖的行星)，用一般环流模式研究了发生完全冻结状态(“雪球”状态)的条件，并特别参考了倾角。结果：1.陆地行星比水行星具有更强的抗冻能力。2.倾斜状态的陆地行星和水生行星对完全冰冻的抵抗力都比垂直状态强。然而，在正直的政权中，对倾斜度的依赖并不明显。3.在倾斜状态的陆地行星上，低纬度地区比中纬度地区更容易结冰。因此，陆地行星很有可能只在低纬地区冻结(低纬度冻结，而不是整个星球冻结)。4.在高倾角的水行星上，与h…的陆地行星相比，低纬冰冻发生在太阳常数较低的地方更高的斜度。在水生行星上，产生低纬度冰冻的太阳常数的范围比在陆地行星上要窄得多。因此，在水族星球上，只有低纬度的冰冻是不太可能的。对古火星的影响：1。为了在古火星的低纬度地区保持湿润的地面，行星必须处于倾斜状态，或者有海洋。然而，在这样的条件下，低纬度地区相对容易被永久降雪覆盖。因此，在目前的倾角条件下，在低纬地区保持未冻结的湿表面比使火星不处于完全冻结状态更加困难。2.如果在火星水循环活跃、平均气温稳步下降的同时倾角发生显著变化，则一定存在一个只有低纬地区被永久积雪覆盖的时期。我们能否从地质记录中找到这样的证据是一个有趣的问题。对行星宜居性的影响：1.富含水的水行星可能不是最适合生命的地方，而有一些水的陆地行星可能比水行星更好，因为水行星很容易陷入完全冻结的状态。2.大倾角行星还是小倾角行星更可取，这是一个难题。大倾角行星抵抗完全冰冻，但经历了严重的季节变化。在45°倾角的水行星上发现了最平静的气候。较少

项目成果

Kimura, H., Y.Abe, A.Abe-Ouchi: "Role of ocean on planetary climate : an implication for ancient-mars"Lunar and Planetary Science (CD-ROM). XXXIII. 1731 (2002)

Kimura, H.、Y.Abe、A.Abe-Ouchi：“海洋对行星气候的作用：对古代火星的影响”月球与行星科学（CD-ROM）。

Abe, Y., A.Abe-Ouchi: "The effect of obliquity and surface condition on the freezing condition of a planet : implications for paleo-mars climate and habitable condition"Lunar and Planetary Science. XXXIV(CD-ROM). 1617 (2003)

Abe，Y.，A.Abe-Ouchi：“倾斜度和表面条件对行星冻结条件的影响：对古火星气候和宜居条件的影响”月球与行星科学。

Yutaka Abe, Ayako Abe-Ouchi: "The freezing condition of a land planet : effect of obliquity"Proceedings of the ISAS Lunar and Planetary Symposium. 35. 21-24 (2002)

Yutaka Abe、Ayako Abe-Ouchi：“陆地行星的冻结条件：倾角的影响”ISAS 月球和行星研讨会论文集。

Kimura, H., Y.Abe, A.Abe-Ouchi: "Role of ocean on planetary climate : an implication for ancient-mars"Lunar and Planetary Science. XXXIII(CD-ROM). 1731 (2002)

Kimura, H.、Y.Abe、A.Abe-Ouchi：“海洋对行星气候的作用：对古代火星的影响”月球与行星科学。

Abe, Y., and A. Abe-Ouchi , edited by H. Mizutani, and M. Kato: "The freezing condition of a land planet : effect of obliquity, in Proceedings of the 35th ISAS Lunar and Planetary Symposium"Institute of Space and Aeronautical Science. 21-24 (2002)

Abe, Y. 和 A. Abe-Ouchi，由 H. Mizutani 和 M. Kato 编辑：“陆地行星的冰冻条件：倾角效应，第 35 届 ISAS 月球和行星研讨会论文集”空间研究所