Multi-season eddy covariance observations of energy, water and carbon fluxes over a suburban area in Swindon, UK

Ward, H.C.; Evans, J.G. ORCID: https://orcid.org/0000-0003-4194-1416; Grimmond, C.S.B.. 2013 Multi-season eddy covariance observations of energy, water and carbon fluxes over a suburban area in Swindon, UK. Atmospheric Chemistry and Physics, 13 (9). 4645-4666. 10.5194/acp-13-4645-2013

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Abstract/Summary

Eddy covariance measurements of the turbulent sensible heat, latent heat and carbon dioxide fluxes for 12 months (2011–2012) are reported for the first time for a suburban area in the UK. The results from Swindon are comparable to suburban studies of similar surface cover elsewhere but reveal large seasonal variability. Energy partitioning favours turbulent sensible heat during summer (midday Bowen ratio 1.4–1.6) and latent heat in winter (0.05–0.7). A significant proportion of energy is stored (and released) by the urban fabric and the estimated anthropogenic heat flux is small but non-negligible (0.5–0.9 MJ m−2 day−1). The sensible heat flux is negative at night and for much of winter daytimes, reflecting the suburban nature of the site (44% vegetation) and relatively low built fraction (16%). Latent heat fluxes appear to be water limited during a dry spring in both 2011 and 2012, when the response of the surface to moisture availability can be seen on a daily timescale. Energy and other factors are more relevant controls at other times; at night the wind speed is important. On average, surface conductance follows a smooth, asymmetrical diurnal course peaking at around 6–9 mm s−1, but values are larger and highly variable in wet conditions. The combination of natural (vegetative) and anthropogenic (emission) processes is most evident in the temporal variation of the carbon flux: significant photosynthetic uptake is seen during summer, whilst traffic and building emissions explain peak release in winter (9.5 g C m−2 day−1). The area is a net source of CO2 annually. Analysis by wind direction highlights the role of urban vegetation in promoting evapotranspiration and offsetting CO2 emissions, especially when contrasted against peak traffic emissions from sectors with more roads. Given the extent of suburban land use, these results have important implications for understanding urban energy, water and carbon dynamics.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.5194/acp-13-4645-2013
Programmes:	CEH Topics & Objectives 2009 - 2012 > Biogeochemistry CEH Topics & Objectives 2009 - 2012 > Water
UKCEH and CEH Sections/Science Areas:	Reynard
ISSN:	1680-7316
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - Official URL link provides full text
NORA Subject Terms:	Ecology and Environment Hydrology Atmospheric Sciences
Related URLs:	Discussion paper
Date made live:	14 Jun 2013 11:50 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/502162

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