The Megacity Lagos and Three Decades of Urban Heat Island Growth
The Megacity Lagos and Three Decades of Urban Heat Island Growth
复制标题
DOI：
10.1175/jamc-d-20-0059.1
复制
发表时间：
2020-12-01
影响因子：
3
通讯作者：
Simm, W.
中科院分区：
文献类型：
--
作者：
Bassett, R.;Young, P. J.;Simm, W.
尼日利亚的拉各斯正在迅速城市化，是世界上发展最快的城市之一，人口每年增加近50万人。然而，通过城市热岛效应（UHI）对拉各斯当地气候的影响还没有得到很好的探讨。考虑到热带地区已经全年高温高湿，微小的变化很可能会使这些地区超过热健康阈值。使用一个完善的模型，但与扩展调查的不确定性，我们探讨了拉各斯最近的城市化对城市热岛的影响。在多物理场评估之后，我们的模拟在2016年2月异常温暖的背景下（在此期间温度经常超过36摄氏度），显示1984年至2016年期间夜间UHI强度平均增加0.44摄氏度。影响的真实规模在空间上被视为整体时间平均UHI超过1摄氏度的区域，从1984年的254公里（2）急剧增加到2016年的1572公里（2）。拉各斯的变暖速度无疑将产生很大的影响，因为人口规模（1.21亿）已经处于过热的危险之中。在农村地区的下风向也发现了明显的变暖和大气边界层高度的变化，这是城市直接造成的。然而，在拉各斯或许多类似的扩张城市，特别是在热带地区，长期气候监测有限。因此，我们的建模只能表明城市化的这种影响，我们强调迫切需要部署仪器。
Lagos, Nigeria, is rapidly urbanizing and is one of the fastest-growing cities in the world, with a population that is increasing at almost 500 000 people per year. Yet the impacts on Lagos's local climate via its urban heat island (UHI) have not been well explored. Considering that the tropics already have year-round high temperatures and humidity, small changes are very likely to tip these regions over heat-health thresholds. Using a well-established model, but with an extended investigation of uncertainty, we explore the impact of Lagos's recent urbanization on its UHI. Following a multiphysics evaluation, our simulations, against the background of an unusually warm period in February 2016 (during which temperatures regularly exceeded 36 degrees C), show a 0.44 degrees C ensemble-time-mean increase in nighttime UHI intensity between 1984 and 2016. The true scale of the impact is seen spatially as the area over which ensemble-time-mean UHIs exceed 1 degrees C was found to increase steeply from 254 km(2) in 1984 to 1572 km(2) in 2016. The rate of warming within Lagos will undoubtedly have a high impact because of the size of the population (121 million) already at risk from excess heat. Significant warming and modifications to atmospheric boundary layer heights are also found in rural areas downwind, directly caused by the city. However, there is limited long-term climate monitoring in Lagos or many similarly expanding cities, particularly in the tropics. As such, our modeling can only be an indication of this impact of urbanization, and we highlight the urgent need to deploy instrumentation.