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000167806 001__ 167806 000167806 005__ 20190101013105.0 000167806 02470 $$2ISI$$a000295674900007 000167806 0247_ $$2doi$$a10.1007/s10546-011-9645-x 000167806 037__ $$aARTICLE 000167806 245__ $$aA Simple Model for the Afternoon and Early Evening Decay of Convective Turbulence Over Different Land Surfaces 000167806 269__ $$a2011 000167806 260__ $$c2011 000167806 336__ $$aJournal Articles 000167806 520__ $$aA simple model to study the decay of turbulent kinetic energy (TKE) in the convective surface layer is presented. In this model, the TKE is dependent upon two terms, the turbulent dissipation rate and the surface buoyancy fluctuations. The time evolution of the surface sensible heat flux is modelled based on fitting functions of actual measurements from the LITFASS-2003 field campaign. These fitting functions carry an amplitude and a time scale. With this approach, the sensible heat flux can be estimated without having to solve the entire surface energy balance. The period of interest covers two characteristic transition sub-periods involved in the decay of convective boundary-layer turbulence. The first sub-period is the afternoon transition, when the sensible heat flux starts to decrease in response to the reduction in solar radiation. It is typically associated with a decay rate of TKE of approximately t −2 (t is time following the start of the decay) after several convective eddy turnover times. The early evening transition is the second sub-period, typically just before sunset when the surface sensible heat flux becomes negative. This sub-period is characterized by an abrupt decay in TKE associated with the rapid collapse of turbulence. Overall, the results presented show a significant improvement of the modelled TKE decay when compared to the often applied assumption of a sensible heat flux decreasing instantaneously or with a very short forcing time scale. In addition, for atmospheric modelling studies, it is suggested that the afternoon and early evening decay of sensible heat flux be modelled as a complementary error function. 000167806 6531_ $$aAfternoon transition 000167806 6531_ $$aCurve fitting 000167806 6531_ $$aDecay of convective turbulence 000167806 6531_ $$aEarly evening transition 000167806 6531_ $$aSensible heat flux 000167806 6531_ $$aSurface layer 000167806 6531_ $$aTurbulent kinetic energy 000167806 6531_ $$aNCCR-MICS 000167806 6531_ $$aNCCR-MICS/ESDM 000167806 700__ $$0242909$$aNadeau, Daniel$$g177729 000167806 700__ $$aPardyjak, Eric R. 000167806 700__ $$0242904$$aHiggins, Chad$$g176727 000167806 700__ $$aFernando, Harinda Joseph S. 000167806 700__ $$0242902$$aParlange, Marc$$g155043 000167806 773__ $$j141$$q301-324$$tBoundary-Layer Meteorology 000167806 8564_ $$s827663$$uhttps://infoscience.epfl.ch/record/167806/files/Nadeau_et_al_BLM_2011_final.pdf$$yn/a$$zn/a 000167806 909C0 $$0252105$$pEFLUM$$xU11028 000167806 909CO $$ooai:infoscience.tind.io:167806$$particle$$qGLOBAL_SET 000167806 917Z8 $$x177729 000167806 917Z8 $$x177729 000167806 917Z8 $$x136301 000167806 917Z8 $$x106058 000167806 917Z8 $$x106058 000167806 937__ $$aEPFL-ARTICLE-167806 000167806 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED 000167806 980__ $$aARTICLE