In dense urban areas, micro-meteorological processes are closely entangled with human activities. This study of the central business district (CBD) analyses an extended (3.5 years) dataset of surface-atmosphere energy exchanges in London. The focus is on the controls on radiation, anthropogenic heat and the turbulent latent and sensible heat fluxes. The impact of the composition and three-dimensional structure of the urban surface, plus the associated anthropogenic activities, are investigated using remote sensing techniques, in-situ observations and modelling at a range of spatial and temporal scales. Radiative properties of urban surfaces are shown to significantly influence the radiation balance. Spectroscopy measurements of a variety of impervious materials illustrate that spectral features, often used to identify materials, are more distinct in the long-wave compared to the short-wave region. The impact of surface geometry and atmospheric conditions on the radiation balance is investigated based on local-scale measurements of broadband radiation components. Long-term radiative and turbulent heat flux measurements suggest a significant amount of energy is supplied by the anthropogenic heat flux, which is affirmed by model results. Micro-scale anthropogenic sources of heat, moisture, and carbon dioxide are addressed by a new filtering technique for the processing of local-scale eddy covariance (EC) fluxes. Surface characteristics and anthropogenic activities influence the energy partitioning of sensible and latent heat: substantial heat storage and additional anthropogenic energy enhance sensible heat exchange, while impervious surfaces restrict moisture availability. Given the limited vegetation in the source area, evaporation is mainly driven by rainwater. The dominant sensible heat and high momentum fluxes favour unstable and neutral atmospheric conditions. This work demonstrates how, even in the complex setting of a CBD, observations provide useful information about processes governing surface-atmosphere exchange that have to be understood in the context of global urbanisation and climate change adaptation strategies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:628491 |
| Date | January 2014 |
| Creators | Kotthaus, Simone |
| Publisher | King's College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://kclpure.kcl.ac.uk/portal/en/theses/implications-of-the-dense-city-centre-to-surfaceatmosphere-exchanges(623b29c6-0080-45b1-b228-66e1b371f73d).html |
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