Abstract
To better understand boundary layer processes and improve hydro-meteorological models it is essential to quantify contributions from different land surface types to the total energy exchange. The effects of urban areas must be represented not only within densely populated towns and cities, but also at the regional scale. A multi-scale field campaign designed to investigate the exchange of energy and mass over suburban land surfaces was undertaken in Swindon, UK. Observations of heat, water vapour and carbon dioxide fluxes suggest Swindon behaves much like a natural landscape during summer, whereas anthropogenic activities dominate in winter. Eddy covariance data collected exhibit broad trends that are in accordance with studies in other locations, whilst marked seasonal contrasts build a more complete picture of the suburban environment.Scintillometry, a ground-based remote sensing technique, estimates turbulent heat fluxes at larger scales (0.1-10 km), comparable to model grids. The conventional single-wavelength method provides the sensible heat flux. Additionally, use of a unique millimetre-wave scintillometer in conjunction with an infrared scintillometer enabled both sensible and latent heat fluxes to be determined. These results represent the first observations of large-scale evaporation over urban areas using scintillometry. The technique is shown to perform reasonably well and recommendations are made for future research. Advantages include spatially integrated fluxes, particularly useful over heterogeneous surfaces where a mosaic of different land cover characteristics can lead to contrasts in surface-atmosphere exchanges.
These observations are used to investigate the controls on evaporation and the behaviour of fluxes at different scales. Particular attention is given to seasonal variability, land cover and the availability of surface moisture and energy. Rapid evaporation directly after rainfall and dew are also explored. With improved understanding of the suburban climate, more accurate predictions can be made regarding the impact of land use development, environmental management schemes and climate change.
| Date of Award | 2013 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Sue Grimmond (Supervisor) & Andreas Baas (Supervisor) |