Interaction between Wind and Temperature Fields in the Planetary Boundary Layer for a Spatially Heterogeneous Surface Heat Flux |
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| Authors: | Hyoung-Jin Kim Yign Noh Siegfried Raasch |
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| Institution: | (1) Institut für Meteorologie und Klimatologie der Universität, Hannover, Germany |
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| Abstract: | Interaction between wind and temperature fields in the planetary boundary layerfor a spatially heterogeneous surface heat flux has been investigated using large-eddysimulation. It is shown that a substantial difference exists in the wind and temperaturefields, depending on whether the directions of the background wind and the surfaceheat flux variation are parallel or perpendicular.When they are parallel to each other, two-dimensional plumes induced by theheterogeneous surface heat flux are easily destroyed by the background wind,and the velocity field is strongly modified by convective eddies compared tothe case when they are perpendicular to each other. This leads to a substantialdifference in the profiles of turbulent kinetic energy and its flux.It also results in a difference between the two cases in the bulk properties of theplanetary boundary layer, such as the entrainment at the top of the planetary boundarylayer and the drag at the bottom, which have important implications for boundary-layermodelling. The difference between the two cases exists even when the background windspeed is as large as 15.0 m s-1. Meanwhile, the contrast between two cases is weakened by the Coriolis force. |
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| Keywords: | Convection Entrainment Heterogeneous surface heat flux Large-eddy simulation Numerical modelling |
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