Understanding the Effects of Land Hydrology, Water Volatility, and Rotation Rate on Clouds, Climate, and Circulation in a Hierarchy of Models

了解模型层次结构中陆地水文、水波动和自转速率对云、气候和环流的影响

• 批准号: 2310364
• 负责人: Jonathan Mitchell
• 金额: $ 65.45万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310364&HistoricalAwards=false
• 关键词: Understanding; Effects; Land; Hydrology; Water

Any first-principles theory of the climate dynamics of the Earth should apply across a broader range of conditions than those found on Earth. Such a theory should predict, for example, how the jet streams would change if the planetary rotation rate were faster or slower, or how clouds and precipitation would change if water were more or less abundant. But such Earth analogs are not readily available to test our theories and help us gain confidence in our understanding of the Earth. Work performed under this award explores the idea that Titan, despite being a moon of Saturn with a surface temperature of -290F, can serve as a useful Earth analog. The analogy is based on observations from the Cassini mission showing that Titan has all the features of an Earth-like hydrological cycle: clouds, rain (often torrential rain from large storms), and surface evaporation from lakes and seas, only with methane instead of water. The Principal Investigator (PI) of this award has developed a "water volatility" parameter that allows methane at Titan-like temperatures to be treated as a kind of water equivalent in simulations of Earth's atmosphere. With this treatment Earth and Titan can be treated as climate systems that fall along a continuum, so that a Titan-like hydrological cycle can be produced from Earth's hydrological cycle by increasing the value of the volatility parameter from one to about three. Two other parameters that must also be changed to produce a Titan-like climate state are the planetary rotation rate, as a day on Titan lasts 16 Earth days, and the amount and distribution of land area, as the tropical latitudes of Titan are entirely land covered. The project tests the extent to which these three parameters suffice to account for the essential differences between Earth-like and Titan-like climates.One issue addressed here is the behavior of low and high clouds under changing water volatility, as previous work by the PI (see AGS-1912673) shows that low clouds tend to descend while high clouds ascend under increasing volatility. The two layers merged at low volatility and are abruptly replaced by a single very thick layer at high volatility. This behavior, which was produced in a single-column atmospheric model, is further explored using a general circulation model and a global storm-resolving model (the ICON model from the Max Planck Institute for Meteorology). Additional work considers changes in atmospheric circulation as parameters are varied from Earth-like to Titan-like. One consideration is that the tropical land cover on Titan causes the bulk of surface evaporation to occur at higher latitudes than on Earth and another is that the slower rotation rate causes different types and sizes of atmospheric wave motions to occur on Titan.Broader impacts of the project include a number of educational activities, one of which is a research cruise on Santa Monica Bay during which students collect data related to the temperature and circulation of the bay. Another is the development and construction of a laboratory device to demonstrate density-driven overturning circulations relevant to oceans and planetary atmospheres. The award also provides support and training for a graduate student, thereby promoting workforce development in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球气候动力学的任何第一原理理论都应在地球上发现的范围更广泛的条件上适用。这样的理论应该预测，例如，如果行星旋转速率更快或较慢，或者，如果水或多或少富含水，云和降水将如何变化。 但是，这种地球类似物不容易就能测试我们的理论并帮助我们对我们对地球的理解有信心。 根据该奖项进行的工作探讨了泰坦（Titan）尽管是土星的月亮，表面温度为-290F，但可以用作有用的地球类似物。 该类比基于卡西尼任务的观察结果，表明泰坦具有类似地球的水文循环的所有特征：云，雨水（通常来自大风暴的雨水）以及湖泊和海洋的表面蒸发，只有甲烷而不是水。 该奖项的主要研究者（PI）开发了一个“挥发性”参数，该参数允许在类似泰坦的温度下将甲烷视为地球大气模拟中的一种水。 使用这种处理，可以将地球和泰坦视为沿连续体落下的气候系统，因此可以通过将波动率参数的价值从一个增加到三个，从地球的水文循环产生。 还必须更改以产生类似泰坦的气候状态的另外两个参数是行星旋转率，因为泰坦的一天持续16个地球日，而土地面积的数量和分布，因为泰坦的热带纬度完全覆盖了土地。 该项目测试这三个参数足以说明类似地球和类似泰坦的气候之间的基本差异。这里解决的一个问题是在不断变化的水波动率下低云和高云的行为，因为PI先前的工作（参见AGS-912673）（参见AGS-912673）表明，低云表明，低云在云层下降时趋于下降，而云层则在增加的云层上升效率下降。 两层以低波动率合并，并以高波动率的一个非常厚的层突然取代。 这种行为是在单柱大气模型中产生的，它是使用通用循环模型和全球风暴分辨模型（Max Planck气象学研究所的图标模型）进一步探索的。 其他工作考虑了大气环流的变化，因为参数从类似地球变为泰坦的变化。 One consideration is that the tropical land cover on Titan causes the bulk of surface evaporation to occur at higher latitudes than on Earth and another is that the slower rotation rate causes different types and sizes of atmospheric wave motions to occur on Titan.Broader impacts of the project include a number of educational activities, one of which is a research cruise on Santa Monica Bay during which students collect data related to the temperature and circulation of the bay. 另一个是实验室装置的开发和构建，以证明与海洋和行星气氛相关的密度驱动的倾覆循环。 该奖项还为研究生提供了支持和培训，从而促进了该研究领域的劳动力发展。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估标准来评估的。