Print Email Facebook Twitter Convective boundary layers driven by nonstationary surface heat fluxes Title Convective boundary layers driven by nonstationary surface heat fluxes Author Van Driel, R. Jonker, H.J.J. Faculty Applied Sciences Department Multi-Scale Physics Date 2011-04-30 Abstract In this study the response of dry convective boundary layers to nonstationary surface heat fluxes is systematically investigated. This is relevant not only during sunset and sunrise but also, for example, when clouds modulate incoming solar radiation. Because the time scale of the associated change in surface heat fluxes may differ from case to case, the authors consider the generic situation of oscillatory surface heat fluxes with different frequencies and amplitudes and study the response of the boundary layer in terms of transfer functions. To this end both a mixed layer model (MLM) and a large-eddy simulation (LES) model are used; the latter is used to evaluate the predictive quality of the mixed layer model. The mixed layer model performs generally quite well for slow changes in the surface heat flux and provides analytical understanding of the transfer characteristics of the boundary layer such as amplitude and phase lag. For rapidly changing surface fluxes (i.e., changes within a time frame comparable to the large eddy turnover time), it proves important to account for the time it takes for the information to travel from the surface to higher levels of the boundary layer such as the inversion zone. As a follow-up to a 1997 study by Sorbjan, who showed that the conventional convective velocity scale is inadequate as a scaling quantity during the decay phase, this paper addresses the issue of defining, in (generic) transitional situations, a velocity scale that is solely based on the surface heat flux and its history. Subject boundary layerlarge eddy simulationsmixed layerradiative-convective equilibriumsurface fluxes To reference this document use: http://resolver.tudelft.nl/uuid:916674e6-2fe6-4d20-a7bd-6362b85e3c3b DOI https://doi.org/10.1175/2010JAS3643.1 Publisher American Meteorological Society ISSN 1520-0469 Source http://journals.ametsoc.org/loi/atsc Source Journal of the atmospheric sciences, 68 (4), 2011 Part of collection Institutional Repository Document type journal article Rights (c) 2011 American Meteorological Society Files PDF driel_jonker_2011.pdf 1.11 MB Close viewer /islandora/object/uuid:916674e6-2fe6-4d20-a7bd-6362b85e3c3b/datastream/OBJ/view