Collaborative Research: Interhemispheric and Zonal Asymmetries of the ITCZ

合作研究：ITCZ 的半球间和区域不对称性

基本信息

批准号：
1934392
负责人：
Shang-Ping Xie
金额：
$ 9.78万
依托单位：
University of California-San Diego Scripps Inst of Oceanography
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-02-01 至 2024-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1934392&HistoricalAwards=false
关键词：
Collaborative Research Interhemispheric Zonal Asymmetries

项目摘要

Satellites views of the earth typically show a narrow band of deep precipitating clouds over the tropical oceans where the trade winds converge. This band, known as the inter-tropical convergence zone, or ITCZ, is generally found north of the equator with a mean latitude of about 6N. Many aspects of the ITCZ including its existence, its role in global atmospheric circulation, and its preference for the Northern Hemisphere can be understood by thinking of the ITCZ as a uniform strip of convection with the same width, central latitude, and rainfall intensity at all longitudes. But this longitudinally averaged view of the ITCZ overlooks substantial variations in ITCZ latitude around the tropics. In particular the ITCZ is found south of the equator in the Indian Ocean and it has a southwest to northeast slope across both the Pacific and Atlantic oceans. The latitude of the ITCZ can thus be anywhere from from 4S to 10N depending on the ocean basin, the longitude within that basin, and the time of year.This project uses combination of observational analysis and carefully designed model simulations to study regional variations in ITCZ latitude and other properties. For instance the northward displacement of the ITCZ in the eastern Pacific has been attributed to the geography of the North and South American coastlines, an idea which can be tested through simulations in which the west coasts of the Americas are mirror images of each other. The importance of oceanic processes is tested using simplified ocean configurations which allow some mechanisms but disable others. Ocean model configurations include a simple motionless "slab" ocean, a modified slab ocean which captures near-surface heat transport driven by surface winds, and a "shallow water" ocean model which allows surface cooling due to the upwelling of cold water from the deep ocean. In addition, the project develops a version of the Community Earth System Model (CESM) in which flux corrections are applied to improve the representation of the ITCZ.The work is of practical interest given the importance of the ITCZ for tropical rainfall as well as its outsized effects on the climate and atmospheric circulation of the earth. Despite its importance the ITCZ is not well simulated in models used for weather prediction and climate change projections, thus a better understanding of ITCZ dynamics could be quite useful for model improvement. The work also has value for the broader research enterprise, as model configurations developed for the project will be openly available for adoption by the worldwide research community. In addition, the award provides support and training for two graduate students, thereby contributing to scientific workforce development.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.

地球的卫星图像通常显示在信风汇聚的热带海洋上空有一条狭窄的深层降水云带。该带被称为热带辐合带 (ITCZ)，通常位于赤道以北，平均纬度约为 6N。 ITCZ 的许多方面，包括它的存在、它在全球大气环流中的作用以及它对北半球的偏好，都可以通过将 ITCZ 视为具有相同宽度、中心纬度和降雨强度的均匀对流带来理解。经度。但这种 ITCZ 的纵向平均视图忽略了热带地区 ITCZ 纬度的巨大变化。特别是，ITCZ 位于赤道以南的印度洋，并具有西南向东北的斜坡，横跨太平洋和大西洋。因此，ITCZ 的纬度可以是从 4S 到 10N 的任意位置，具体取决于洋盆、该盆地内的经度以及一年中的时间。该项目结合观测分析和精心设计的模型模拟来研究 ITCZ 的区域变化纬度和其他属性。例如，东太平洋的 ITCZ 向北移动被归因于北美和南美海岸线的地理，这一想法可以通过美洲西海岸互为镜像的模拟来检验。海洋过程的重要性是通过简化的海洋配置来测试的，该配置允许某些机制但禁用其他机制。海洋模型配置包括简单的静止“板状”海洋、改进的板状海洋（捕获由表面风驱动的近地表热传输）以及“浅水”海洋模型（由于来自深海的冷水上涌而允许表面冷却）海洋。此外，该项目还开发了社区地球系统模型 (CESM) 的一个版本，其中应用通量修正来改善 ITCZ 的代表性。鉴于 ITCZ 对热带降雨的重要性及其影响，这项工作具有实际意义。对地球气候和大气环流产生巨大影响。尽管 ITCZ 很重要，但它在天气预报和气候变化预测模型中并未得到很好的模拟，因此更好地了解 ITCZ 动态对于模型改进可能非常有用。这项工作对于更广泛的研究企业也具有价值，因为为该项目开发的模型配置将公开供全球研究界采用。此外，该奖项还为两名研究生提供支持和培训，从而为科学劳动力的发展做出贡献。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。