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Effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer
Author(s) -
Kopec Marta K.,
Malinowski Szymon P.,
Piotrowski Zbigniew P.
Publication year - 2016
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2903
Subject(s) - radiative cooling , wind shear , atmospheric sciences , radiative transfer , turbulence , boundary layer , convective boundary layer , cloud top , turbulence kinetic energy , radiative flux , inversion (geology) , entrainment (biomusicology) , convection , geology , environmental science , richardson number , meteorology , planetary boundary layer , mechanics , wind speed , physics , geomorphology , satellite , quantum mechanics , astronomy , structural basin , rhythm , acoustics
The effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer (STBL) were investigated via a set of large‐eddy simulations. The set‐up of the numerical experiments was based on Flight TO13 from the Physics of Stratocumulus Top (POST) field campaign, in which sensible and latent heat fluxes at the surface were small and thermodynamic conditions prevented cloud‐top entrainment instability. The results demonstrate that the presence of radiative cooling invigorated convective circulations across the STBL and sharpened the inversion above the cloud, while wind shear at the top of the STBL was a source of turbulence in the capping inversion and caused dilution of the cloud top. The flux and gradient Richardson numbers in the capping inversion and in the topmost layer of the cloud were nearly critical. Analysis of the turbulent kinetic energy (TKE) budget and its transport indicated that turbulence in the inversion capping the cloud was produced locally by wind shear and was dynamically decoupled from the turbulence driven by convective circulations across the STBL. Similar conclusions were derived for the topmost part of the cloud.