Flux and turbulence measurements at a dense urban site in Marseille: heat, mass (water, carbon dioxide) and momentum

CSB Grimmond, Jennifer Salmond, TR Oke, B Offerle, A Lemonsu

    Research output: Contribution to journalArticle

    185 Citations (Scopus)

    Abstract

    Eddy covariance (EC) observations above the densely built-up center of Marseille during the Experience sur site pour contraindre les modeles de pollution atmospherique et de transport d'emissions (ESCOMPTE) summertime measurement campaign extend current understanding of surface atmosphere exchanges in cities. The instrument array presented opportunities to address issues of the representativeness of local-scale fluxes in urban settings. Separate EC systems operated at two levels, and a telescoping tower allowed the pair to be exposed at two different sets of heights. The flux and turbulence observations taken at the four heights, stratified by wind conditions (mistral wind and sea breeze), are used to address the partitioning of the surface energy balance in an area with large roughness elements. The turbulent sensible heat flux dominates in the daytime, although the storage heat flux is a significant term that peaks before solar noon. The turbulent latent heat flux is small but not negligible. Carbon dioxide fluxes show that this central city district is almost always a source, but the vegetation reduces the magnitude of the fluxes in the afternoon. The atmosphere in such a heavily developed area is rarely stable. The turbulence characteristics support the empirical functions proposed by M. Roth.
    Original languageEnglish
    JournalJournal of Geophysical Research: Atmospheres
    Volume109
    Issue numberD24
    DOIs
    Publication statusPublished - 1 Jan 2004

    Keywords

    • stability
    • carbon dioxide fluxes
    • turbulence
    • urban climate
    • energy balance
    • eddy covariance

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