College of Landscape Architecture & Arts, Northwest A&F University, Yangling, 712100, China.
College of Landscape Architecture & Arts, Northwest A&F University, Yangling, 712100, China.
J Environ Manage. 2022 Sep 1;317:115346. doi: 10.1016/j.jenvman.2022.115346. Epub 2022 May 26.
How to maximize the cooling effect of urban parks in hot extremes has been closely linked to well-beings of citizens. Few studies have quantified urban parks' cooling effect in hot extremes from both maximum and accumulative perspectives. Here, we explored 65 urban parks' cooling effect based on spatially continuous cooling curves using multiple satellite images of Greater Xi'an (34°06' ∼34°34' N, 108°33' ∼109°15' E), one of China's metropolises with frequent hot extremes during July and August in 2019 summer. From maximum perspective, the urban parks cool down as far as 151.4 m, and covering 63.62 ha area, circa five times their own area in hot extremes; from accumulative perspective, the average cooling intensity is 0.78 °C along the whole continuous cooling distance spectrum, accumulated as 153.87 °C•m. And the urban parks show stronger accumulative cooling effect in hot extremes than the relative moderate temperatures. The cooling range could be maximized in large parks with dense trees, also in complex-shaped parks with strong interaction with surrounding environment. Small parks such as neighborhood parks located in the densely populated area are with maximum efficiency, cooling down about nine times their own area, which could serve as highly efficient cooling networks. Enhancing vegetation growth and coupling both blue and green infrastructures are always effective to increase accumulative cooling intensity in hot extremes. Our findings provide nature-based solutions (NBS) to counteracting heat stresses from the intense and frequent hot extremes in the future, also helpful for energy saving in the continuing climate change scenario.
如何最大限度地发挥城市公园在极端高温下的降温效果，一直与市民的福祉密切相关。很少有研究从最大和累积的角度量化极端高温下城市公园的降温效果。在这里，我们利用 2019 年夏季 7 月和 8 月西安（34°06' ∼34°34' N，108°33' ∼109°15' E）的多个卫星图像，探索了 65 个城市公园的降温效果，该城市是中国经常发生极端高温的特大城市之一。从最大的角度来看，城市公园的降温范围可达 151.4 m，覆盖面积达 63.62 公顷，大约是其在极端高温下自身面积的五倍；从累积的角度来看，整个连续冷却距离谱上的平均冷却强度为 0.78°C，累积为 153.87°C•m。在极端高温下，城市公园的累积冷却效果比相对温和的温度更强。在树木茂密的大型公园和与周围环境互动强烈的复杂形状的公园中，可以最大限度地扩大冷却范围。位于人口密集区的小型公园（如邻里公园）的最大效率，冷却面积约为自身面积的九倍，可以作为高效的冷却网络。加强植被生长和耦合蓝绿基础设施始终是提高极端高温下累积冷却强度的有效方法。我们的研究结果为应对未来强烈和频繁的极端高温提供了基于自然的解决方案（NBS），也有助于应对持续气候变化情景下的节能问题。
