A Simple Model for the Afternoon and Early Evening Decay of Convective Turbulence Over Different Land Surfaces

Nadeau, Daniel F.; Pardyjak, Eric R.; Higgins, C. W.; Fernando, H. J. S.; Parlange, Marc B.

doi:10.1007/s10546-011-9645-x

Cited by 65 publications

(121 citation statements)

References 35 publications

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“…The abrupt collapse of the absolute temporal TKE change (|dē/dt|) at hub height (Fig. 3c), which signifies the onset of the transition (Nadeau et al 2011), coincides with the stability change. The above evidence suggests a distinct evening transition before sunset, consistent with the observations of Grimsdell and Angevine (2002).…”

Section: Evening Transition Characterizationmentioning

confidence: 76%

“…An abrupt decay in turbulent kinetic energy (TKE), associated with the collapse of daytime turbulence, and the sign changes in the surface heat flux Q H , are indicators of the "early evening transition" (Nadeau et al 2011). The delay between the time when Q H becomes negative and the TKE decay has been quantified previously (Nieuwstadt and Brost 1986;Sorbjan 1997;BlayCarreras et al 2014).…”

Section: The Evening Boundary Layer and Turbine Wakesmentioning

confidence: 98%

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Observing and Simulating Wind-Turbine Wakes During the Evening Transition

Lee

Lundquist

2017

Boundary-Layer Meteorol

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Wind-turbine-wake evolution during the evening transition introduces variability to wind-farm power production at a time of day typically characterized by high electricity demand. During the evening transition, the atmosphere evolves from an unstable to a stable regime, and vertical stratification of the wind profile develops as the residual planetary boundary layer decouples from the surface layer. The evolution of wind-turbine wakes during the evening transition is examined from two perspectives: wake observations from single turbines, and simulations of multiple turbine wakes using the mesoscale Weather Research and Forecasting (WRF) model. Throughout the evening transition, the wake's wind-speed deficit and turbulence enhancement are confined within the rotor layer when the atmospheric stability changes from unstable to stable. The height variations of maximum upwind-downwind differences of wind speed and turbulence intensity gradually decrease during the evening transition. After verifying the WRF-model-simulated upwind wind speed, wind direction and turbulent kinetic energy profiles with observations, the wind-farm-scale wake evolution during the evening transition is investigated using the WRF-model wind-farm parametrization scheme. As the evening progresses, due to the presence of the wind farm, the modelled hub-height wind-speed deficit monotonically increases, the relative turbulence enhancement at hub height grows by 50%, and the downwind surface sensible heat flux increases, reducing surface cooling. Overall, the intensifying wakes from upwind turbines respond to the evolving atmospheric boundary layer during the evening transition, and undermine the power production of downwind turbines in the evening.

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Section: Evening Transition Characterizationmentioning

confidence: 76%

Section: The Evening Boundary Layer and Turbine Wakesmentioning

confidence: 98%

Observing and Simulating Wind-Turbine Wakes During the Evening Transition

Lee

Lundquist

2017

Boundary-Layer Meteorol

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“…Several methodologies have been used to study the CBL: large eddy simulation (LES) numerical experiments (Moeng, 1984;Nieuwstadt and Brost, 1986;Cuijpers and Duynkerke, 1993;Sorbjan, 2007), mixed-layer model (MLM) (Tennekes, 1973;Tennekes and Driedonks, 1981;Fedorovich,4516 E. Blay-Carreras et al: Role of the RL and subsidence on the development and evolution of the CBL laboratory experiments (Deardorff et al, 1980;Fedorovich et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…During the night, a shallower stable boundary layer (SBL) with less turbulence intensity exists near the surface (Nieuwstadt, 1984;Carlson and Stull, 1986;Mahrt, 1998;Beare et al, 2006). Between this layer and the free atmosphere (FA), there may exist a neutrally stratified layer resulting from the decay of turbulence of the previous day CBL.…”

Section: Introductionmentioning

confidence: 99%

“…These two periods are difficult to study due to their rapid variability. The afternoon transition has been studied by using observations and/or numerical simulations (Sorbjan, 1997;Cole and Fernando, 1998;Edwards et al, 2006;Pino et al, 2006a;Angevine, 2007;Nadeau et al, 2011). However, there are still many unknowns during this period: the presence of significant vertical movements in late afternoon, which appear even with very small surface heat flux; the influence of boundary layer processes in the turbulence decay; and what the processes are that govern the decrease of the boundary-layer depth .…”

Section: Introductionmentioning

confidence: 99%

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Role of the residual layer and large-scale subsidence on the development and evolution of the convective boundary layer

et al. 2014

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Abstract. Observations, mixed-layer theory and the DutchLarge-Eddy Simulation model (DALES) are used to analyze the dynamics of the boundary layer during an intensive operational period (1 July 2011) of the Boundary Layer Late Afternoon and Sunset Turbulence campaign. Continuous measurements made by remote sensing and in situ instruments in combination with radio soundings, and measurements done by remotely piloted aircraft systems and two manned aircrafts probed the vertical structure and the temporal evolution of the boundary layer during the campaign. The initial vertical profiles of potential temperature, specific humidity and wind, and the temporal evolution of the surface heat and moisture fluxes prescribed in the models runs are inspired by some of these observations. The research focuses on the role played by the residual layer during the morning transition and by the large-scale subsidence on the evolution of the boundary layer. By using DALES, we show the importance of the dynamics of the boundary layer during the previous night in the development of the boundary layer at the morning. DALES numerical experiments including the residual layer are capable of modeling the observed sudden increase of the boundary-layer depth during the morning transition and the subsequent evolution of the boundary layer. These simulations show a large increase of the entrainment buoyancy flux when the residual layer is incorporated into the mixed layer. We also examine how the inclusion of the residual layer above a shallow convective boundary layer modifies the turbulent kinetic energy budget.Large-scale subsidence mainly acts when the boundary layer is fully developed, and, for the studied day, it is necessary to be considered to reproduce the afternoon observations.Finally, we also investigate how carbon dioxide (CO 2 ) mixing ratio stored the previous night in the residual layer plays a fundamental role in the evolution of the CO 2 mixing ratio during the following day.

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Convective boundary layer evolution from lidar backscatter and its relationship with surface aerosol concentration at a location of a central China megacity

Kong

2015

JGR Atmospheres

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Based on the 1 min backscatter ratio R profiles from the all-day lidar measurements in Wuhan, China (30.5°N, 114.4°E), hourly convective boundary layer (CBL) height was calculated with the variance method. The calculated CBL height sequence displays the regular diurnal cycle of the CBL top. The prevalent mixing process within the CBL is also revealed. During the CBL growth period, the backscatter ratio R falls visibly with increasing altitude and has large variance within the CBL, suggesting that more abundant aerosol particles from lower altitudes are being transported upward and being mixed with the local background or advected aerosol layers. During the CBL quasistationary period, R tends to be vertically uniform, and its variance reaches a daytime minimum within the CBL, indicating that the vertical homogenization of aerosol particles produced by the convectively driven mixing reaches its maximum. During the afternoon and early evening transition period, the vertical uniformity of R weakens and the variance enlarges again, implying that the reduced convectively driven mixing fails to maintain a high vertical homogeneity. When the 1 min R profiles were plotted together in terms of each 1 h interval, the fluctuating R curves at heights around the CBL top looked like a "node", representing the structure of the entrainment zone between the CBL and the free troposphere. The moving node depicts the evolution of the entrainment zone. The diurnal variation of the CBL height shows an obvious seasonal dependence which coincides with the annual variation of the local surface temperature. The surface fine particle concentration generally has a more complex diurnal cycle than that expected from the CBL-dilution/CBL-accumulation effect. But, it shows a strong annual variation which is out of phase with respect to that of the monthly mean maximum CBL height. This tends to suggest that the seasonal behavior of the surface fine particle concentration mainly depends on the seasonal variation in available volume (determined by the CBL height) for aerosol dispersion.

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A Simple Model for the Afternoon and Early Evening Decay of Convective Turbulence Over Different Land Surfaces

Cited by 65 publications

References 35 publications

Observing and Simulating Wind-Turbine Wakes During the Evening Transition

Observing and Simulating Wind-Turbine Wakes During the Evening Transition

Role of the residual layer and large-scale subsidence on the development and evolution of the convective boundary layer

Convective boundary layer evolution from lidar backscatter and its relationship with surface aerosol concentration at a location of a central China megacity

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