Impact of anthropogenic heat emissions on London's temperatures
Impact of anthropogenic heat emissions on London's temperatures
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DOI：
10.1002/qj.2144
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发表时间：
2014-01-01
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.;Hamilton, I.;Belcher, S. E.
我们研究了人为热通量在伦敦城市热岛上的作用。为此，将随时间变化的人为热通量添加到城市地表能量平衡参数化中，即英国气象局统一模式的1公里分辨率版本中实施的气象局-瑞丁城市地表交换计划(MORUSES)。人为热通量来自伦敦的能源需求数据，并在模型的1公里网格上指定；它包括日和季节时间尺度上的变化。通过春季和冬季的对比，说明了冬季较大的人为热通量的影响，以及热力学在不同季节所起的不同作用。地表能量平衡将人为热量导入城市地表加热，由于城市地表热容量大，城市地表升温缓慢。在这些额外的变暖中，约有三分之一用于增加向外发射的长波辐射，只有约三分之二用于增加使大气变暖的显性热通量。人为热通量对冬季屏面温度的影响较大，部分原因是人为热通量较大，部分原因是冬季边界层较浅。对于本文研究的特定冬季个例，伦敦上空的人为热通量整夜保持着一个混合良好的边界层，而周围的乡村边界层则变得非常稳定的层结。这一发现可能会对冬季的空气质量产生重要影响。总体而言，人为热通量的加入略微改善了模式模拟与屏温测量之间的对比，表明人为热通量正开始成为伦敦城市热岛的一个重要因素。
We investigate the role of the anthropogenic heat flux on the urban heat island of London. To do this, the time-varying anthropogenic heat flux is added to an urban surface-energy balance parametrization, the Met Office-Reading Urban Surface Exchange Scheme (MORUSES), implemented in a 1 km resolution version of the UK Met Office Unified Model. The anthropogenic heat flux is derived from energy-demand data for London and is specified on the model's 1 km grid; it includes variations on diurnal and seasonal time-scales. We contrast a spring case with a winter case, to illustrate the effects of the larger anthropogenic heat flux in winter and the different roles played by thermodynamics in the different seasons. The surface-energy balance channels the anthropogenic heat into heating the urban surface, which warms slowly because of the large heat capacity of the urban surface. About one third of this additional warming goes into increasing the outgoing long-wave radiation and only about two thirds goes into increasing the sensible heat flux that warms the atmosphere. The anthropogenic heat flux has a larger effect on screen-level temperatures in the winter case, partly because the anthropogenic flux is larger then and partly because the boundary layer is shallower in winter. For the specific winter case studied here, the anthropogenic heat flux maintains a well-mixed boundary layer through the whole night over London, whereas the surrounding rural boundary layer becomes strongly stably stratified. This finding is likely to have important implications for air quality in winter. On the whole, inclusion of the anthropogenic heat flux improves the comparison between model simulations and measurements of screen-level temperature slightly and indicates that the anthropogenic heat flux is beginning to be an important factor in the London urban heat island.