Interactions between coherent eddies in the lower convective boundary layer

A. G. Williams, J. M. Hacker

    Research output: Contribution to journalArticle

    37 Citations (Scopus)

    Abstract

    The processes of interaction between the atmospheric surface and mixed layers in daytime convective conditions over land are studied using a data set obtained during flights by an instrumented aircraft. Profiles of partitioned run-averaged statistics and examples of time series plots are discussed in the light of results from a recently published study by the authors, in which the average structure and flow within coherent eddies was reconstruced using a compositing technique. This evidence is used to support a conceptual model of the mechanisms of interaction between surface-layer plumes and mixed-layer thermal columns. The divergent flow created near the surface by the downdraft arms of the large-scale mixed-layer circulation patterns, forces the development of lines of convergence in the surface layer (the so-called "thermal walls"), which channel air into the bases of the mixed-layer thermals. Plumes progressively group and merge together with height in the surface and free convection layers, and move along these convergence lines toward large "collector" plumes at the intersection points, or "hubs". Above the "hubs" are the thermals, and air parcels originating from plumes and their environment are strongly mixed as they rise, leading to an increased difficulty of the conditional sampling method to distinguish between them. The observed influence of mixed-layer convective processes far down into the surface layer, and the form of the averaged profiles, supports recent refinements of the theory of surface-layer structure suggested in Kader and Yaglom (1990).

    Original languageEnglish
    Pages (from-to)55-74
    Number of pages20
    JournalBoundary-Layer Meteorology
    Volume64
    Issue number1-2
    DOIs
    Publication statusPublished - Mar 1993

    Fingerprint Dive into the research topics of 'Interactions between coherent eddies in the lower convective boundary layer'. Together they form a unique fingerprint.

  • Cite this