Dynamics of Large-scale Monsoons and their Response to Climate Changes

大范围季风动态及其对气候变化的响应

• 批准号: 1462544
• 负责人: Simona Bordoni
• 金额: $ 40.66万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1462544&HistoricalAwards=false
• 关键词: Dynamics; Large; scale; Monsoons; their

Monsoons are prominent features of the large-scale circulation of the Earth's atmosphere, sustaining densely populated, rapidly growing and socially vulnerable regions in the tropics and subtropics. This project seeks to improve understanding of the essential processes that are involved in monsoons and that mediate their response to climate change. The premise of the project is that monsoons can be viewed as seasonal migrations of zones of tropical convection and their associated large-scale overturning circulations, and that the fundamental dynamics of such convectively-driven overturning can be understood in terms of angular momentum and energy balance constraints. Under this premise the research begins by examining the behavior of seasonally migrating convection zones in simplified "aquaplanet" simulations in which the earth's surface is entirely covered by oceans and there are no land-sea contrasts. These model simulations are followed by further simulations with idealized continents, and finally results from these simulations are compared with realistic climate simulations from the Climate Model Intercomparison Project version 5 (CMIP5). Specific issues to be addressed include the relatively sudden onset of the monsoon, the delay of monsoon onset with increasing global mean temperature found in model simulations, and the relationship between global mean temperature and the strength of the overturning circulation. Goals of the project are to 1) investigate how monsoons change in a wide range of climates, in order to place past, present and future changes in a broad context; 2) determine how monsoons change in simulations in which complexity is progressively increased; starting from aquaplanet simulations with no land-masses to simulations with idealized continental geometries; and 3) use the conceptual understanding emerging from the idealized simulations to evaluate state-of-the-art general circulation models, and better constrain future projections.The work has broader impacts due to the importance of monsoons for agriculture and water resources in densely populated regions of the world. Understanding how monsoons change with changing climate is both a priority and a major challenge in climate science, and the present work may contribute both by improving our ability to interpret and evaluate projections of monsoon change from climate models, and in improving the models used for such projections. In addition, the project will support and train a graduate student, thereby providing for the next generation of researchers in this area, and three undergraduate students will be hosted for summer research.

季风是地球大气大规模环流的显著特征，维持着热带和亚热带人口稠密、快速增长和社会脆弱的地区。 该项目旨在提高对季风所涉及的基本过程的认识，这些过程是季风对气候变化作出反应的中介。 该项目的前提是，季风可以被视为热带对流区及其相关的大规模翻转环流的季节性迁移，这种对流驱动的翻转的基本动力学可以理解的角动量和能量平衡的限制。 在这个前提下，研究开始于在简化的“水行星”模拟中检查季节性迁移的对流区的行为，其中地球表面完全被海洋覆盖，没有陆地和海洋的对比。这些模式模拟之后，进一步模拟与理想化的大陆，最后从这些模拟的结果进行了比较，从气候模式相互比较项目第5版（CMIP 5）的现实气候模拟。 要解决的具体问题包括季风的相对突然的爆发，季风爆发的延迟与模型模拟中发现的全球平均温度的增加，以及全球平均温度和翻转环流的强度之间的关系。该项目的目标是：（1）调查季风如何在广泛的气候条件下变化，以便将过去、现在和未来的变化放在一个广泛的背景下;（2）确定季风如何在模拟中变化，其中复杂性逐渐增加;从没有陆地的水行星模拟开始，到理想化的大陆几何形状模拟;以及3）使用从理想化模拟中产生的概念性理解来评估最先进的大气环流模式，并更好地约束未来的预测。由于季风对世界人口密集地区的农业和水资源的重要性，这项工作具有更广泛的影响。 了解季风如何随着气候变化而变化是气候科学的一个优先事项和重大挑战，目前的工作可能有助于提高我们解释和评估气候模型预测季风变化的能力，并改进用于此类预测的模型。 此外，该项目将支持和培训一名研究生，从而为这一领域的下一代研究人员提供支持，并将接待三名本科生进行夏季研究。