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Impact of anthropogenic heat emissions on London's temperatures
Author(s) -
Bohnenstengel S. I.,
Hamilton I.,
Davies M.,
Belcher S. E.
Publication year - 2013
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2144
Subject(s) - heat flux , sensible heat , environmental science , flux (metallurgy) , atmospheric sciences , urban heat island , energy balance , boundary layer , parametrization (atmospheric modeling) , climatology , planetary boundary layer , atmosphere (unit) , energy flux , meteorology , heat transfer , geography , geology , mechanics , physics , materials science , thermodynamics , quantum mechanics , radiative transfer , astronomy , metallurgy
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.

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