The positive impacts of urban greenery on human health and wellbeing are well documented in scholarly literature. The focus has mostly been on residential greenery or availability and access to recreational green spaces. The importance of greenery in travel environments has received much less attention. Furthermore, little consideration has been given to temporal dynamics, although research suggests that greenery benefits are not uniformly distributed over different seasons or daytimes. In this study, we aimed to fill these knowledge gaps by systematically assessing travel and residential greenery in 86 European cities. Moreover, we quantified the impact of seasonality and variation in daytime length by using an open data approach at the pan-European level. First, we compared travel and residential greenery using monthly NDVI composites derived from high-resolution Sentinel-2 satellite imagery. In addition, we explored the temporal dynamics of greenery and adjusted NDVI values accordingly. The results demonstrated that travel environments have significantly lower greenery levels than residential environments in European cities. Overall, we found a latitudinal gradient from low to high travel greenery in southern Europe compared to Nordic cities. The findings also indicated that accounting for temporal variations, especially in northeastern Europe, has significant impact on the measured availability of travel greenery. We conclude that travel environment greenery and temporal variations should not be overlooked in exposure studies because they can lead to a biased understanding of greenery availability and related spatial disparities. Our findings can therefore serve as a methodological and policy benchmark for greening goals in European cities.

中文翻译：

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欧洲 86 个城市的出行绿化时间变化


城市绿化对人类健康和福祉的积极影响在学术文献中得到了很好的记录。重点主要集中在住宅绿化或可用性以及获得休闲绿地的机会上。绿色植物在旅行环境中的重要性受到的关注要少得多。此外，很少考虑时间动态，尽管研究表明，绿色植物的好处在不同的季节或白天并不均匀分布。在这项研究中，我们旨在通过系统评估 86 个欧洲城市的出行和住宅绿化来填补这些知识空白。此外，我们通过在泛欧洲层面使用开放数据方法量化了季节性和白天长度变化的影响。首先，我们使用来自高分辨率 Sentinel-2 卫星图像的月度 NDVI 合成图像比较了旅行和住宅绿化。此外，我们探索了绿色植物的时间动态并相应地调整了 NDVI 值。结果表明，在欧洲城市，出行环境的绿化水平明显低于住宅环境。总体而言，我们发现与北欧城市相比，南欧的旅行绿地从低到高的纬度梯度。研究结果还表明，考虑时间变化，尤其是在东北欧，对测量的旅行绿色植物的可用性有重大影响。我们得出的结论是，在暴露研究中不应忽视旅行环境、绿色植物和时间变化，因为它们可能导致对绿色植物可用性和相关空间差异的偏见理解。因此，我们的研究结果可以作为欧洲城市绿化目标的方法和政策基准。