近日，美国西北太平洋国家实验室Chakraborty TC和Qian Yun团队研究发现，灌溉减少了北美城市白天的热应力。该研究于2025年1月9日发表于国际一流学术期刊《自然—地球科学》杂志上。

据了解，灌溉对热压力的影响存在相当大的不确定性，部分原因在于热应力指数的选择。此外，现有模拟的规模无法适当地解决人口中心或云层的问题，及其对人类作用的潜在影响。

研究团队利用多年对流允许和城市解析区域气候模拟，证明灌溉可以缓解北美1600多个城镇的夏季热应力。这适用于大多数与生理相关的热应力指数。灌溉的影响因气候带而异，位于大量灌溉田地附近的干旱城市，气象中心的灌溉信号更为明显。

通过成分归因框架，研究组发现，灌溉引起的湿球温度变化，通常在地球科学中被视为湿热应力的代理，跨越气候区时与湿球温度的相应变化，表现出相反的迹象，这是评估室内和室外热风险的更完整的指标。

相比之下，城市化引起的局部湿球温度，和全球湿球温度变化具有相同的标志。研究结果证明了灌溉和热应力之间的复杂关系，凸显了在评估人口规模人类影响的潜力时，制定适当的热应力指标的重要性。

附：英文原文

Title: Daytime urban heat stress in North America reduced by irrigation

Author: Chakraborty, TC, Qian, Yun, Li, Jianfeng, Leung, L. Ruby, Sarangi, Chandan

Issue&Volume: 2025-01-09

Abstract: There is considerable uncertainty regarding the impact of irrigation on heat stress, partly stemming from the choice of heat stress index. Moreover, existing simulations are at scales that cannot appropriately resolve population centres or clouds and thus the potential for human impacts. Using multi-year convection-permitting and urban-resolving regional climate simulations, we demonstrate that irrigation alleviates summertime heat stress across more than 1,600 urban clusters in North America. This holds true for most physiologically relevant heat stress indices. The impact of irrigation varies by climate zone, with more notable irrigation signals seen for arid urban clusters that are situated near heavily irrigated fields. Through a component attribution framework, we show that irrigation-induced changes in wet-bulb temperature, often used as a moist heat stress proxy in the geosciences, exhibit an opposite sign to the corresponding changes in wet bulb globe temperature—a more complete index for assessing both indoor and outdoor heat risk—across climate zones. In contrast, the local changes in both wet-bulb and wet bulb globe temperature due to urbanization have the same sign. Our results demonstrate a complex relationship between irrigation and heat stress, highlighting the importance of using appropriate heat stress indices when assessing the potential for population-scale human impacts.

DOI: 10.1038/s41561-024-01613-z

Source: https://www.nature.com/articles/s41561-024-01613-z