Ocean Surfaces on Snowball Earth

雪球地球上的海洋表面

• 批准号: 0739779
• 负责人: Stephen Warren
• 金额: $ 95.63万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-15 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0739779&HistoricalAwards=false
• 关键词: Ocean; Surfaces; Snowball; Earth

AbstractPI: Stephen G. WarrenProposal Number: 0739779 Title: Ocean Surfaces on Snowball EarthIntellectual merit: Evidence of episodes of extreme glaciation during the Neoproterozoic time (600-800 million years ago) lead to formulation of the Snowball Earth hypothesis in the early 1990's. A central but controversial idea of this hypothesis is that ice covered nearly the entire ocean for periods of up to several million years. Climate models differ greatly in their simulations of this time period suggesting everything from an ice free tropical ocean, to a "hard" snowball or fully frozen ocean to "slushy" scenario in between. It is known that climate models are highly sensitive to prescribed albedos although modelers have yet to settle on a preferred treatment in part because the full spectral albedos of the likely surfaces are uncertain. To provide clearer guidance in this realm, the Office of Polar Programs, Antarctic Integrated System Science Program has made this award to study the albedo of snow and ice surfaces that may have been pivotal to initiation and maintenance of an ice-covered ocean. Albedo may have also been key factor in determining sea ice thickness, thus light transmission to the water below and so governing possible refugia for the more delicate eukaryotic life forms that are known to have survived this time period. It is argued that today only Antarctica provides sufficiently analogous ice surfaces to the specialized ones that are thought to have occurred under a Snowball Earth scenario. A combination of field observations of cold (meaning less than -23C) snow-free sea ice, salt encrusted sea-ice surfaces and blue (subject to net ablation) glacial ice, laboratory experiments (various salt encrusted ice surfaces) and modeling (of radiative transfer and conditions required for potential refugia under thin, light transmitting ice in marginal seas such as the Mediterranean) will be carried out to test the viability of the Snowball Earth hypothesis. In collaboration with climate modelers, the field and laboratory results will be applied to better constraining global scale models of Snowball Earth. Broader impacts: This basic research program is aimed at understanding past extreme climate conditions on Earth. Such conditions have implications for biological evolution; while prokaryotes could readily survive the challenge, it is not clear how the more susceptible eukaryotes did. The measurements should also provide information for sea-ice and glacial-ice in the modern environment that may be relevant to projecting future climate. They might also provide insights for the understanding of ice and salts surfaces on the moons of Jupiter and Saturn. The project will involve an undergraduate in laboratory observations and a graduate student whose PhD thesis will derive from this study. This research program integrates the expertise of an atmospheric scientist, sea-ice scientist and glaciologist. One of the coPIs is a member of an underrepresented group (female) in sea ice physics. The sea-ice component is collaborative with a New Zealand International Polar Year project focused on seasonal evolution of sea-ice properties.

中文摘要：斯蒂芬G. Warren提案编号：0739779标题：知识价值：新元古代（6 - 8亿年前）极端冰川作用的证据导致了20世纪90年代早期雪球地球假说的形成。 这一假说的一个核心但有争议的观点是，冰几乎覆盖了整个海洋长达数百万年。 气候模型在模拟这一时期时有很大的不同，从无冰的热带海洋到“硬”雪球或完全冻结的海洋，再到介于两者之间的“泥泞”情景。 众所周知，气候模型对规定的反照率高度敏感，尽管建模者尚未确定首选处理方法，部分原因是可能表面的全光谱反照率不确定。 为了在这一领域提供更明确的指导，南极综合系统科学计划极地项目办公室颁发了这个奖项，以研究冰雪表面的融化，这可能是冰覆盖海洋的启动和维持的关键。 反照率也可能是决定海冰厚度的关键因素，因此光传输到下面的水，从而管理可能的避难所，为更微妙的真核生命形式，已知已经生存在这个时期。 有人认为，今天只有南极洲提供了足够类似的冰表面，被认为是在雪球地球的情况下发生的专门的。结合对寒冷地区的实地观察，（意味着低于-23摄氏度）无雪海冰，盐结壳海冰表面和蓝色（受净消融）冰川冰，实验室实验（各种盐结壳冰表面）和建模（辐射转移和薄，在地中海等边缘海域的透光冰）将进行测试雪球地球假说的可行性。 与气候建模者合作，实地和实验室结果将用于更好地约束雪球地球的全球尺度模型。 更广泛的影响：这项基础研究计划旨在了解地球上过去的极端气候条件。这些条件对生物进化有影响;虽然原核生物可以很容易地在挑战中生存下来，但尚不清楚更敏感的真核生物是如何做到的。这些测量还应提供现代环境中海冰和冰川冰的信息，这可能与预测未来气候有关。它们还可能为了解木星和土星卫星上的冰和盐表面提供见解。该项目将涉及一名实验室观察的本科生和一名研究生，他们的博士论文将来自这项研究。该研究计划整合了大气科学家，海冰科学家和冰川学家的专业知识。其中一名coPI是海冰物理学中代表性不足的群体（女性）的成员。海冰部分是与新西兰国际极地年项目合作开展的，该项目侧重于海冰特性的季节性演变。