Greater aridity increases the magnitude of urban nighttime vegetation-derived air cooling
Greater aridity increases the magnitude of urban nighttime vegetation-derived air cooling
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DOI：
10.1088/1748-9326/abdf8a
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发表时间：
2021-03-01
影响因子：
6.7
通讯作者：
Jenerette, G. Darrel
中科院分区：
文献类型：
--
作者：
Ibsen, Peter C.;Borowy, Dorothy;Jenerette, G. Darrel
城市夜间气温高增加了全球人民的健康风险和经济脆弱性。虽然最近的研究强调了城市植被的夜间热缓解效应，但城市之间的植被引起的城市夜间降温的幅度和变化性差异很大。我们假设，城市植被引起的夜间空气冷却是由植被密度驱动的，其效果是通过增加蒸腾调节干燥。我们通过在美国八个城市部署微气候传感器来测试这一假设，并调查整个夏季夜间气温和城市植被的关系。城市植被降低了所有城市的夜间气温。植被降温幅度增加作为干旱的函数，在最潮湿的城市，迈阿密，佛罗里达州，在最干旱的城市，拉斯维加斯，内华达州的最低冷却幅度为1.4摄氏度和5.6摄氏度。与城市之间的差异一致，所有城市在热浪期间的冷却效果都有所增加。对于经历夏季季风的城市，凤凰城和图森，亚利桑那州，冷却幅度更大，在更干旱的前季风季节比在更潮湿的季风期间。我们的研究结果把以前的测量植被夜间城市降温到一个连贯的生理框架依赖于植物蒸腾的巨大差异。这项工作通过提供一个框架，将城市植被作为环境正义工具，为城市热风险规划提供信息，并有助于确定城市植被在何处以及何时对降低夜间温度产生最大影响。
High nighttime urban air temperatures increase health risks and economic vulnerability of people globally. While recent studies have highlighted nighttime heat mitigation effects of urban vegetation, the magnitude and variability of vegetation-derived urban nighttime cooling differs greatly among cities. We hypothesize that urban vegetation-derived nighttime air cooling is driven by vegetation density whose effect is regulated by aridity through increasing transpiration. We test this hypothesis by deploying microclimate sensors across eight United States cities and investigating relationships of nighttime air temperature and urban vegetation throughout a summer season. Urban vegetation decreased nighttime air temperature in all cities. Vegetation cooling magnitudes increased as a function of aridity, resulting in the lowest cooling magnitude of 1.4 degrees C in the most humid city, Miami, FL, and 5.6 degrees C in the most arid city, Las Vegas, NV. Consistent with the differences among cities, the cooling effect increased during heat waves in all cities. For cities that experience a summer monsoon, Phoenix and Tucson, AZ, the cooling magnitude was larger during the more arid pre-monsoon season than during the more humid monsoon period. Our results place the large differences among previous measurements of vegetation nighttime urban cooling into a coherent physiological framework dependent on plant transpiration. This work informs urban heat risk planning by providing a framework for using urban vegetation as an environmental justice tool and can help identify where and when urban vegetation has the largest effect on mitigating nighttime temperatures.