title: Effects of urban density on carbon dioxide exchanges: Observations of dense urban, suburban and woodland areas of southern England.
abstract: Anthropogenic and biogenic controls on the surface-atmosphere exchange of CO2 are explored for three different environments. Similarities are seen between suburban and woodland sites during summer, when photosynthesis and respiration determine the diurnal pattern of the CO2 flux. In winter, emissions from human activities dominate urban and suburban fluxes; building emissions increase during cold weather, while traffic is a major component of CO2 emissions all year round. Observed CO2 fluxes reflect diurnal traffic patterns (busy throughout the day (urban); rush-hour peaks (suburban)) and vary between working days and non-working days, except at the woodland site. Suburban vegetation offsets some anthropogenic emissions, but 24-h CO2 fluxes are usually positive even during summer. Observations are compared to estimated emissions from simple models and inventories. Annual CO2 exchanges are significantly different between sites, demonstrating the impacts of increasing urban density (and decreasing vegetation fraction) on the CO2 flux to the atmosphere.
authors.affiliation: Department of Meteorology, University of Reading, Reading, RG6 6BB, UK; Centre for Ecology and Hydrology, Wallingford, Oxfordshire, OX10 8BB, UK. Electronic address: h.c.ward@reading.ac.uk.
authors.forename: H C
authors.initials: HC
authors.lastname: Ward
authors.affiliation: Department of Meteorology, University of Reading, Reading, RG6 6BB, UK; Department of Geography, King's College London, London, WC2R 2LS, UK.
authors.forename: S
authors.initials: S
authors.lastname: Kotthaus
authors.affiliation: Department of Meteorology, University of Reading, Reading, RG6 6BB, UK.
authors.forename: C S B
authors.initials: CS
authors.lastname: Grimmond
authors.affiliation: Department of Geography, King's College London, London, WC2R 2LS, UK.
authors.forename: A
authors.initials: A
authors.lastname: Bjorkegren
authors.affiliation: Forest Research, Centre for Forestry and Climate Change, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK.
authors.forename: M
authors.initials: M
authors.lastname: Wilkinson
authors.affiliation: Department of Meteorology, University of Reading, Reading, RG6 6BB, UK.
authors.forename: W T J
authors.initials: WT
authors.lastname: Morrison
authors.affiliation: Centre for Ecology and Hydrology, Wallingford, Oxfordshire, OX10 8BB, UK.
authors.forename: J G
authors.initials: JG
authors.lastname: Evans
authors.affiliation: Forest Research, Centre for Forestry and Climate Change, Alice Holt Lodge, Farnham, Surrey, GU10 4LH, UK.
authors.forename: J I L
authors.initials: JI
authors.lastname: Morison
authors.affiliation: Scuola di Ingegneria, Università degli Studi della Basilicata, 85100, Potenza, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Iamarino
mesh_terms: D001272:Atmosphere; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D002947:Cities / Q000706:statistics & numerical data*; D004739:England; D065928:Forests; D006801:Humans; D008962:Models, Theoretical; D010788:Photosynthesis; D011156:Population Density; D012621:Seasons; D014197:Trees / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide
keywords: Carbon emissions; Emissions inventory; Human impact; Land use change; Net ecosystem exchange