Collaborative Research: Forced Trends in the Tropical Pacific and Global Tropical Cyclones

合作研究：热带太平洋和全球热带气旋的强迫趋势

• 批准号: 2217618
• 负责人: Chia-Ying Lee
• 金额: $ 83.02万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2217618&HistoricalAwards=false
• 关键词: Collaborative; Research; Forced; Trends; Tropical

The temperature contrast between the "warm pool" region of the western equatorial Pacific and the "cold tongue" in the east is remarkable: visitors to the Solomon islands find sea surface temperatures (SSTs) above 80F while visitors to the Galapagos don wetsuits to go snorkeling. Naturally the temperature contrast has a variety of effects on the weather and climate of the tropics, one of which is the relative abundance of hurricanes (also called typhoons and TCs, for tropical cyclones) which are more abundant in the western Pacific than anywhere else in the world. The influence of the SST contrast can be seen in comparisons between El Nino events, in which the contrast weakens due to warming in the cold tongue region, and La Nina events, which strengthen the contrast. El Nino years feature fewer TCs in the western Pacific and more in the central and eastern Pacific, with the opposite pattern in La Nina years.The influence of El Nino and La Nina on TCs and other aspects of tropical weather and climate begs the question: will the equatorial Pacific SST contrast be strengthened or weakened by greenhouse gas-induced global warming? The evidence is mixed since climate models generally show weakening as the earth warms but observations show strengthening over the past few decades. The mismatch could be due to the internal variability of the climate system, which operates even as greenhouse gas increases warm the world. But it is also possible that climate model biases, in particular the bias of a cold tongue which is too cold and too extensive, lead to incorrect simulations of the effects of greenhouse warming.Work under this award addresses the possible effect of the cold tongue bias on the simulated SST contrast change using a technique called flux adjustment, in which the exchange of heat and moisture between the atmosphere and ocean is modified to eliminate the cold tongue bias in present-day climate simulations. The flux-adjusted climate model is then used to simulate the response of the SST contrast to greenhouse gas increases. The work is carried out with the Community Earth System Model version 2 (CESM2).The effects of an El Nino-like or La Nina-like SST warming pattern on tropical cyclones is difficult to assess from climate model simulations because the resolution of climate models is not typically high enough to simulate TCs. One strategy pursued here is to simulate TCs using shorter simulations from a high-resolution atmosphere-only model which is run over the SST warming pattern produced by the climate model. Another is to use the Columbia HAZard model (CHAZ), an empirical TC model developed by the lead Principal Investigator (PI). CHAZ uses large-scale atmospheric conditions from the climate model or observational datasets to predict the tracks and intensities of "synthetic" TCs that are initiated at random based on a TC genesis index.The work has societal as well as scientific value given the consequences of warming-induced changes in TC behavior. It is clear that warming causes the most intense hurricanes to become stronger and more destructive, thus efforts to anticipate changes in the distribution of TCs across the Pacific are valuable for climate adaptation and disaster risk reduction. The PIs have strong ties to the World Bank, the reinsurance industry, and other relevant stakeholders through the Columbia World project. They also conduct extensive media outreach on climate change-related topics including TC risk. In addition, the project supports a postdoctoral fellow and a graduate student, thereby promoting the future workforce 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.

赤道太平洋西部的“暖池区”和东部的“冷舌区”之间的温度反差非常显著：所罗门群岛的游客发现海面温度(SST)高于80华氏度，而加拉帕戈斯群岛的游客穿着潜水服潜水。自然，温度差异对热带地区的天气和气候有多种影响，其中之一是飓风(热带气旋也称为台风和热带气旋)的相对丰富，而西太平洋比世界其他任何地方都更丰富。在厄尔尼诺事件和拉尼娜事件之间的对比中，可以看出海温对比度的影响。厄尔尼诺事件由于冷舌区变暖而对比度减弱，拉尼娜事件则加强了对比度。厄尔尼诺年西太平洋TCS较少，中、东太平洋TCS较多，拉尼娜年则相反。厄尔尼诺和拉尼娜对TCS和热带天气气候其他方面的影响引出一个问题：温室气体导致的全球变暖会增强还是减弱赤道太平洋海温的对比度？证据是复杂的，因为气候模型通常显示随着地球变暖而减弱，但观察显示在过去几十年里增强了。这种不匹配可能是由于气候系统的内部可变性，即使在温室气体增加使世界变暖的情况下，气候系统也在运行。但也有可能是气候模型的偏差，特别是太冷和太广泛的冷舌偏差，导致对温室气体变暖影响的错误模拟。该奖项的工作使用一种称为通量调节的技术来解决冷舌偏差对模拟的SST对比度变化的可能影响，在该技术中，大气和海洋之间的热量和水分交换被修改，以消除当今气候模拟中的冷舌偏差。然后使用通量调整的气候模式来模拟海温对温室气体增加的响应。这项工作是利用共同体地球系统模式第2版(CESM2)进行的。由于气候模式的分辨率通常不足以模拟热带气旋，因此很难从气候模式模拟中评估类似厄尔尼诺或拉尼娜的海温变暖模式对热带气旋的影响。这里追求的一种策略是使用高分辨率纯大气模式的较短模拟来模拟TCS，该模式运行在气候模式产生的SST变暖模式上。另一种是使用哥伦比亚风险模型(CHAZ)，这是一种由首席首席调查员(PI)开发的经验TC模型。CHAZ使用气候模型或观测数据集中的大尺度大气条件来预测基于TC成因指数随机启动的“合成”TC的轨迹和强度。考虑到气候变暖导致TC行为变化的后果，这项工作具有社会和科学价值。很明显，气候变暖导致最强烈的飓风变得更强、更具破坏性，因此，努力预测太平洋上TC分布的变化对于适应气候和减少灾害风险是很有价值的。私人投资机构通过哥伦比亚世界项目与世界银行、再保险行业和其他相关利益攸关方建立了牢固的联系。他们还就气候变化相关主题进行广泛的媒体宣传，包括TC风险。此外，该项目还支持一名博士后研究员和一名研究生，从而促进了该研究领域未来的劳动力队伍。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

State of the Climate in 2022. The Tropics

2022 年气候状况。热带地区

• DOI: 10.1175/bams-d-23-0078.1
• 发表时间: 2023
• 期刊: Bulletin of the American Meteorological Society
• 影响因子: 8
• 作者: Diamond, Howard J.;Schreck, Carl J.;Allgood, Adam;Becker, Emily J.;Blake, Eric S.;Bringas, Francis G.;Camargo, Suzana J.;Chen, Lin;Coelho, Caio A.S.;Fauchereau, Nicolas
• 通讯作者: Fauchereau, Nicolas

An Update on the Influence of Natural Climate Variability and Anthropogenic Climate Change on Tropical Cyclones

• DOI: 10.1016/j.tcrr.2023.10.001
• 发表时间: 2023-10
• 期刊: Tropical Cyclone Research and Review
• 影响因子: 2.9
• 作者: Suzana J. Camargo;Hiroyuki Murakami;N. Bloemendaal;S. Chand;Medha S. Deshpande;Christian Dominguez-Sarmiento-Christian-Domi

Near-term tropical cyclone risk and coupled Earth system model biases

近期热带气旋风险和耦合地球系统模型偏差

• DOI: 10.1073/pnas.2209631120
• 发表时间: 2023
• 期刊: Proceedings of the National Academy of Sciences
• 作者: Sobel, Adam H.;Lee, Chia-Ying;Bowen, Steven G.;Camargo, Suzana J.;Cane, Mark A.;Clement, Amy;Fosu, Boniface;Hart, Megan;Reed, Kevin A.;Seager, Richard
• 通讯作者: Seager, Richard