Collaborative Research: Geoengineering of Urban Green Infrastructure to Improve Outdoor Livability

美国城市人口面临着空气质量下降和热应力升高的问题，尤其是在热浪天气下。这两种环境压力因素影响着人类健康，对城市宜居性提出了新的挑战。城市绿色基础设施作为建筑环境的一个组成部分，被认为是可能改善空气质量和减少热应力的有效缓解战略之一。过去的研究广泛地评估了UGI对热量或空气污染的影响，但最近的一些研究考虑了热量和空气污染之间的非微不足道的相互作用。这种相互作用提出了一个问题，即在实施统一用户指标时，是否总能实现减少热量和空气污染。因此，本项目旨在阐明UGIs如何在多个空间尺度上影响城市热环境与空气污染之间的相互作用。此外，该项目将开发一种新的方法，通过考虑热应激和空气污染对人类健康的影响来评估UGI的设计策略。该项目将解决两个科学问题：1)极端高温事件的发生如何影响热量和空气质量的联合影响？2)在正常和极端高温条件下，不同的UGI设计策略预期的缓解结果是什么？为了回答这些问题，研究小组将应用天气研究与预报模型（WRF），结合化学（Chem）和城市冠层模型（UCM），改进UGI的表示。将利用正常夏季和高温条件下的观测资料对耦合模式进行评价。纽约市和凤凰城目前UGI在缓解热应激和空气污染方面的效果将通过考虑衡量联合健康影响的综合统计来量化。将对社区和城市尺度上的不同UGI实现（空间无差别vs.目标）进行评估。研究内容将包括：(1)在城市冠层模型中对邻近尺度的城市植被进行综合表征；（ii）基于综合统计的基于过程的方法，在社区和城市尺度上评估热应激和空气污染对健康的影响；（iii）通过与景观设计师和利益相关者的协同活动，在多个空间尺度上融合宜居性评估、城市气候和城市规划。先进的数值大气物理和化学模型，结合分析和量化UGI设计方案的新方法，旨在为工程解决方案和环境可持续性提供新的思路。预期的主要研究成果有：(1)基于过程的方法系统地考察局地气候带和城市层面植被的影响；(2)可扩展到城市层面的社区尺度的城市景观规划策略组合；(3)基于热污染耦合的新科学为室外宜居性提供了一种新的客观指标。与景观设计师和利益相关者的密切互动将促进公众对城市绿色基础设施重要性的认识，特别是对可持续和健康的户外宜居性具有重要影响的环境压力源。在项目结束时，将建立一个具有不同UGI情景的城市宜居性指标共享数据库，供其他学术研究人员、公民和利益相关者使用。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。

Urban population in the United States is confronted with degraded air quality and elevated thermal stress, especially under heat waves. These two environmental stressors impact human health impose new challenges to urban livability. Urban green infrastructure (UGI), as an integral part of the built environment, has been considered as one of the effective mitigation strategies for potentially improving air quality and reducing thermal stress. Past research extensively evaluated the impact of UGI on either heat or air pollution separately but a few recent studies account for the non-trivial interactions between heat and air pollution. Such interactions raise the question of whether heat and air pollution mitigation is always achievable when implementing UGIs. This project therefore aims to elucidate how UGIs impact the interactions between urban thermal environment and air pollution across multiple spatial scales. Additionally, this project will develop a new method for evaluating the design strategies of UGI by considering the human health implications of heat stress and air pollution combined. The project will address two scientific questions: 1) How does the occurrence of extreme heat events affect the joint impacts of heat and air quality? 2) What mitigation outcomes are expected given different design strategies of UGI under normal and extreme heat conditions? To answer these questions, the research team will apply the Weather Research and Forecast model (WRF) coupled with chemistry (Chem) and urban canopy model (UCM) with improved representation of UGI. The coupled model will be evaluated with observational data under normal summer and high temperature conditions. The effects of the present UGI in both NYC and Phoenix in mitigating heat stress and air pollution will be quantified by considering a combined statistic that measures the joint health impacts. Different UGI implementations (spatially undifferentiated vs. targeted) at both the neighborhood and city scales will be evaluated. The study will include: (i) integrated representation of urban vegetation at the neighborhood scale in the urban canopy model; (ii) a process-based method based on a combined statistic to evaluate the health impacts of heat stress and air pollution at the neighborhood and city scales; (iii) fusing livability assessment, urban climates, and urban planning on multiple spatial scales through synergistic activities with landscape architects and stakeholders. Advanced numerical atmospheric physics and chemistry modeling, in conjunction with a new approach for analysis and quantification of UGI design scenarios is targeted to shed new light on engineering solutions and environmental sustainability. The main research outcomes anticipated are: (1) a process-based approach to systematically examine the influence of vegetation for both local climate zones and city level; (2) a portfolio of urban landscape planning strategies at the neighborhood scale, that is scalable to the city level; (3) a novel objective indicator of outdoor livability informed by new science based on heat- pollution coupling. Close interaction with landscape architects and stakeholders will facilitate public awareness of the importance of urban green infrastructure, particularly for environmental stressors that have important consequences of sustainable and healthy outdoor livability. An initiative for establishing a shared database for the urban livability indicators with different UGI scenarios will be established at the end of the project, accessible to other academic researchers, citizens, and stakeholders.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.