Simulations of the London urban heat island
Simulations of the London urban heat island
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DOI：
10.1002/qj.855
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发表时间：
2011-07-01
影响因子：
8.9
通讯作者：
Belcher, S. E.
中科院分区：
文献类型：
--
作者：
Bohnenstengel, S. I.;Evans, S.;Belcher, S. E.
我们使用MET办公室的统一模型对伦敦的气象学进行了模拟，该模型具有新的，复杂的表面能量平衡计划，以代表城市表面，称为摩尔斯。模拟是用代表的城市表面进行的，并用草地代替了城市表面，以计算当地气象学的城市增量。当地的城市效应在一定程度上通过了陆上流的通过，该流程传播了泰晤士河河口和整个城市，下午在伦敦稍微冷却了伦敦。当城市增量高达5 K时，屏幕级温度的验证表明了令人鼓舞的一致性。然后使用模型结果来检查塑造伦敦大气边界层的空间和时间结构的因素。模拟调和了各种研究中显示的城市热岛（UHI）的时间演变的差异，并证明UHI随时间的变化在很大程度上取决于城市的提取。市中心下风的UHI在夜间显示UHI的减少，而市中心的UHI保持恒定。最后，市中心上风的位置上的UHI不断增加。在晚上过渡时期，UHI的大小随着城市的获取而增加。当边界层浅时，晚上的城市增量最大。日落后，边界层的经历持续变暖，因为释放了城市织物的热量，并且整个城市都会出现弱对流的边界层。城市土地利用分数是对明智的热通量和由此产生的城市增量对空间结构的主要控制区域。版权所有（C）2011皇家气象学会和英国皇冠版权，大都会办公室
We present simulations of London's meteorology using the Met Office Unified Model with a new, sophisticated surface energy-balance scheme to represent the urban surfaces, called MORUSES. Simulations are performed with the urban surfaces represented and with the urban surfaces replaced with grass in order to calculate the urban increment on the local meteorology. The local urban effects were moderated to some extent by the passage of an onshore flow that propagated up the Thames estuary and across the city, cooling London slightly in the afternoon. Validations of screen-level temperature show encouraging agreement to within 1-2 K, when the urban increment is up to 5 K. The model results are then used to examine factors shaping the spatial and temporal structure of London's atmospheric boundary layer. The simulations reconcile the differences in the temporal evolution of the urban heat island (UHI) shown in various studies and demonstrate that the variation of UHI with time depends strongly on the urban fetch. The UHI at a location downwind of the city centre shows a decrease in UHI during the night, while the UHI at the city centre stays constant. Finally, the UHI at a location upwind of the city centre increases continuously. The magnitude of the UHI by the time of the evening transition increases with urban fetch. The urban increments are largest at night, when the boundary layer is shallow. The boundary layer experiences continued warming after sunset, as the heat from the urban fabric is released, and a weakly convective boundary layer develops across the city. The urban land-use fraction is the dominant control on the spatial structure in the sensible heat flux and the resulting urban increment, although even the weak advection present in this case study is sufficient to advect the peak temperature increments downwind of the most built-up areas. Copyright (C) 2011 Royal Meteorological Society and British Crown Copyright, the Met Office