LExEn: Extraordinary Climates of Earth-Like Planets: GCM Simulations at High Obliquity

LExEn：类地行星的非凡气候：高倾角的 GCM 模拟

• 批准号: 9977980
• 负责人: Darren Williams
• 金额: $ 19.65万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-15 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9977980&HistoricalAwards=false
• 关键词: LExEn; Extraordinary; Climates; Earth; Like

P.I.: Williams, Darren Proposal Number: AST-9977980The obliquity of Earth is stabilized by the size and proximity of the Moon. The formation of the Moon through a giant impact may be a relatively improbable outcome of planetary accretion. Thus, many Earth-like planets around other stars may not be well configured for spin-axis stability, which could allow their obliquities to vary wildly and to episodically approach 90 degrees. A natural question is whether Earth-like planets with high obliquities might still be climatically suitable for life. Past work using an energy-balance climate model has revealed that climate at high obliquity would be made regionally severe by large-scale seasonal changes to insolation received in the middle and upper latitudes. The extraordinary seasonal temperature fluctuations that would result might be damaging to many forms of life that depend on liquid water. The response of other Earth-like planets will depend primarily on their land-sea fractions and continental geographies, which affect the rate of seasonal heating and cooling, as well as levels of greenhouse gases such as H2O and CO2. Dr. Williams and colleagues will use a three-dimensional general circulation model (GCM) to simulate extreme climates at high obliquity. These models are better suited to examining changes to climate caused by high obliquity because they simulate heat transport by winds and other processes more realistically than do simpler one-dimensional models. The GMC that will be employed includes a coupled ice-sheet model equipped to monitor the growth and ablation of glaciers. This will enable an investigation of whether high obliquity could have been the cause for low-latitude glaciation in the Precambrian Era of Earth's history. A suite of experiments will be performed for different continental arrangements, CO2 levels, and obliquities to place constraints on possible climates of early Earth and on the habitability of planets around other stars.

P.I.：Williams，Darren 提案编号：AST-9977980 地球的倾斜度通过月球的大小和距离来稳定。 通过巨大撞击形成月球可能是行星吸积相对不可能的结果。 因此，许多围绕其他恒星运行的类地行星可能没有很好地配置自旋轴稳定性，这可能导致它们的倾角变化很大，并偶尔接近 90 度。 一个自然的问题是，具有高倾角的类地行星在气候上是否仍然适合生命存在。 过去使用能量平衡气候模型的研究表明，由于中高纬度地区日照的大规模季节性变化，高倾角地区的气候会变得更加严峻。 由此产生的异常季节性温度波动可能会损害许多依赖液态水的生命形式。 其他类地行星的反应将主要取决于它们的陆地-海洋部分和大陆地理，这会影响季节性升温和降温的速率，以及水和二氧化碳等温室气体的水平。 威廉姆斯博士和同事将使用三维大气环流模型（GCM）来模拟高倾角的极端气候。 这些模型更适合检查高倾角引起的气候变化，因为它们比简单的一维模型更真实地模拟风和其他过程的热传输。 将采用的 GMC 包括一个耦合冰盖模型，用于监测冰川的生长和消融。 这将有助于调查高倾角是否可能是地球历史前寒武纪低纬度冰川作用的原因。 将对不同的大陆排列、二氧化碳水平和倾角进行一系列实验，以限制早期地球可能的气候以及其他恒星周围行星的宜居性。