P2C2: Tropical Pacific Influences on Atmospheric Blocking across Climates

大气阻塞事件是一种持续的天气模式，通常是高压系统，使中纬度急流和风暴转移数天至数周，并可能与热浪、寒流、干旱和洪水等极端天气有关。大气阻塞及其相关极端事件对人为气候变化的响应存在很大的不确定性，包括它们的频率、强度和持续时间，以及它们受气候变率的调节。El Niño-Southern涛动（ENSO）事件期间热带太平洋平均气候状态和异常对大气阻塞的影响然而，这些影响因ENSO“风味”（东太平洋或中太平洋）而异。因此，阻断预估的部分不确定性是由于热带太平洋平均状态和ENSO多样性及其潜在相互作用的预估变化的不确定性。本项目旨在研究ENSO多样性、大气阻塞和极端事件在观测和现有和新的目标模式实验中的关系。通过古气候模式-代理综合，该项目将有可能对偏差进行评估，并为受热带影响的大气阻塞和相关极端天气的未来预测制定约束条件。这项工作的重点是对大气阻塞与相关极端天气之间的关系进行系统和分层调查，具体考虑热带太平洋平均气候的不同状态和ENSO多样性的影响。为此，研究人员将把大气阻塞特征和极端事件频率与热带太平洋在多个时间尺度（多年代际、年际）的状态联系起来，并通过综合对GCM当前和过去气候实验的诊断分析、新的高分辨率（~15公里）模式实验（旨在隔离热带太平洋的作用）、极端天气的统计建模和古气候代理记录来诊断潜在的机制。这项研究将为热带对中纬度极端事件的影响提供新的见解，并允许对古气候代用物和模式进行定量综合，以评估代表这些关系的模式技能。最终的目标是设计出能够减少模式在模拟外部强迫阻塞变化时的不确定性的度量，换句话说，基于热带太平洋平均状态和多样性的模拟技能计算阻塞预估的约束。潜在的更广泛的影响包括一个综合、验证和解释过去气候和现代观测的综合框架，以评估区域和全球尺度上的未来气候预测。该项目有可能改善极端天气的预测和与气候变化和变率、大气阻塞和极端事件交叉相关的风险评估，并开发知识和资源，这些知识和资源正越来越多地被学术机构、政府机构和私营部门研发公司（包括保险公司、银行和咨询公司）使用。该研究将为研究生和本科生提供科学培训，使他们了解第三章-亚裔美国人和美洲原住民太平洋岛民服务机构（AANAPI）的天气和气候风险分析新技术。此外，将开发一个新的在线推广模块，纳入两年一次的SOEST开放日活动，面向K-12参观者和公众（约10分钟的活动），旨在提高人们对ENSO口味独特影响的认识和理解。这个新模块将被设计为一个ENSO影响游戏，在这个游戏中，玩家将放置一个与不同ENSO口味相对应的海面温度异常，这将改变急流在板上的位置。然后，他们将被要求猜测ENSO在多个地点的影响，包括夏威夷（潮湿/干燥，温暖/寒冷），因为它们与急流的变化有关，并将根据命中和未命中分配分数。该模块将公开共享，供全国各地的教育工作者使用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Atmospheric blocking events are persistent weather patterns, most often high-pressure systems, that divert the mid-latitude jet stream and storms for days to weeks and can be associated with extreme weather such as heat waves, cold spells, droughts, and flooding. There is significant uncertainty surrounding the response of atmospheric blocking and its related extreme events to anthropogenic climate change, including their frequency, intensity, and duration, as well as their modulation by climate variability. The mean climate state and anomalies of the tropical Pacific during El Niño-Southern Oscillation (ENSO) events influence atmospheric blocking; however, these impacts vary depending on the ENSO “flavor” (Eastern or Central Pacific). Thus, part of the uncertainty in blocking projections is due to uncertainties in the projected changes in both the tropical Pacific mean state and ENSO diversity and their potential interactions. This project aims to investigate the relationship between ENSO diversity, atmospheric blocking and extreme events in observations and existing and new targeted model experiments. Via a paleoclimate model-proxy synthesis, the project will potentially enable the assessment of biases and the development of constraints for future projections of atmospheric blocking and associated weather extremes as they are influenced by the tropics.The work focuses on a systematic and hierarchical investigation of the relationship between atmospheric blocking and associated weather extremes that will specifically consider the impact of different states of tropical Pacific mean climate and of ENSO diversity. To this end, the researchers will relate atmospheric blocking characteristics and extreme event frequency to the state of the tropical Pacific at multiple time scales (multidecadal, interannual) and, diagnose the underlying mechanisms via a synthesis of diagnostic analysis of GCM present-day and past climate experiments, new high-resolution (~15km) model experiments designed to isolate the role of the tropical Pacific, statistical modeling of weather extremes, and paleoclimate proxy records. This investigation will offer new insights into the impact of the tropics on midlatitude extreme events and allow for a quantitative synthesis of paleoclimate proxies and models to assess model skill in representing these relationships. The ultimate goal is to devise metrics that reduce model uncertainty in simulations of externally-forced changes in blocking, in other words calculate constraints for blocking projections based on simulation skill of tropical Pacific mean state and diversity. The potential broader impacts include a comprehensive framework for integration, validation and interpretation of past climate and modern observations to evaluate future climate projections at regional and global scales. This project has the potential to improve the prediction of extreme weather and assessment of risk associated with the intersection of climate change and variability, atmospheric blocking, and extreme events, and develops knowledge and resources that are increasingly being used by academic institutions, government agencies, and private-sector R&D companies, including insurance companies, banks, and consulting firms.The research will provide scientific training for graduate and undergraduate students on new technologies on weather and climate risk analysis in Title III - Asian American and Native American Pacific Islander-Serving Institutions (AANAPI). Additionally, a new online outreach module will be developed to be incorporated in the biennial SOEST Open House Activities for K-12 visitors and the general public (~10-minute activities), designed to raise awareness and understanding of the distinct impacts of ENSO flavors. This new module will be designed as an ENSO impacts game, where the players will place a Sea Surface Temperature anomaly corresponding to different ENSO flavors, which will change the position of the jet stream on the board. They will then be asked to guess the ENSO impacts in multiple locations, including Hawaii (wet/dry, warm/cold) as they relate to changes in the jet stream, and will be assigned scores based on hits and misses. The module will be shared publicly to be used by educators across the country.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.